Eliminate every mention of PG_CACHED pages from the comments in the machine-
independent layer of the virtual memory system. Update some of the nearby comments to eliminate redundancy and improve clarity. In vm/vm_reserv.c, do not use hyphens after adverbs ending in -ly per The Chicago Manual of Style. Update the comment in vm/vm_page.h defining the four types of page queues to reflect the elimination of PG_CACHED pages and the introduction of the laundry queue. Reviewed by: kib, markj Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D8752
This commit is contained in:
alc
parent
722dbb7b5c
commit
023ed8da8d
@ -1858,9 +1858,7 @@ vm_map_submap(
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* limited number of page mappings are created at the low-end of the
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* specified address range. (For this purpose, a superpage mapping
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* counts as one page mapping.) Otherwise, all resident pages within
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* the specified address range are mapped. Because these mappings are
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* being created speculatively, cached pages are not reactivated and
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* mapped.
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* the specified address range are mapped.
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*/
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static void
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vm_map_pmap_enter(vm_map_t map, vm_offset_t addr, vm_prot_t prot,
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@ -1356,7 +1356,7 @@ retry:
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goto retry;
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}
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/* vm_page_rename() will handle dirty and cache. */
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/* vm_page_rename() will dirty the page. */
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if (vm_page_rename(m, new_object, idx)) {
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VM_OBJECT_WUNLOCK(new_object);
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VM_OBJECT_WUNLOCK(orig_object);
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@ -1446,7 +1446,7 @@ vm_object_scan_all_shadowed(vm_object_t object)
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/*
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* Initial conditions:
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*
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* We do not want to have to test for the existence of cache or swap
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* We do not want to have to test for the existence of swap
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* pages in the backing object. XXX but with the new swapper this
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* would be pretty easy to do.
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*/
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@ -1590,8 +1590,7 @@ vm_object_collapse_scan(vm_object_t object, int op)
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* backing object to the main object.
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*
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* If the page was mapped to a process, it can remain mapped
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* through the rename. vm_page_rename() will handle dirty and
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* cache.
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* through the rename. vm_page_rename() will dirty the page.
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*/
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if (vm_page_rename(p, object, new_pindex)) {
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next = vm_object_collapse_scan_wait(object, NULL, next,
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@ -79,17 +79,6 @@
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*
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* vm_object_t Virtual memory object.
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*
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* The root of cached pages pool is protected by both the per-object lock
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* and the free pages queue mutex.
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* On insert in the cache radix trie, the per-object lock is expected
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* to be already held and the free pages queue mutex will be
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* acquired during the operation too.
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* On remove and lookup from the cache radix trie, only the free
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* pages queue mutex is expected to be locked.
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* These rules allow for reliably checking for the presence of cached
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* pages with only the per-object lock held, thereby reducing contention
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* for the free pages queue mutex.
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*
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* List of locks
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* (c) const until freed
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* (o) per-object lock
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@ -1409,9 +1409,7 @@ vm_page_replace(vm_page_t mnew, vm_object_t object, vm_pindex_t pindex)
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*
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* Note: we *always* dirty the page. It is necessary both for the
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* fact that we moved it, and because we may be invalidating
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* swap. If the page is on the cache, we have to deactivate it
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* or vm_page_dirty() will panic. Dirty pages are not allowed
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* on the cache.
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* swap.
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*
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* The objects must be locked.
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*/
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@ -2042,18 +2040,18 @@ unlock:
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} else if (level >= 0) {
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/*
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* The page is reserved but not yet allocated. In
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* other words, it is still cached or free. Extend
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* the current run by one page.
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* other words, it is still free. Extend the current
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* run by one page.
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*/
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run_ext = 1;
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#endif
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} else if ((order = m->order) < VM_NFREEORDER) {
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/*
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* The page is enqueued in the physical memory
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* allocator's cache/free page queues. Moreover, it
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* is the first page in a power-of-two-sized run of
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* contiguous cache/free pages. Add these pages to
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* the end of the current run, and jump ahead.
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* allocator's free page queues. Moreover, it is the
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* first page in a power-of-two-sized run of
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* contiguous free pages. Add these pages to the end
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* of the current run, and jump ahead.
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*/
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run_ext = 1 << order;
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m_inc = 1 << order;
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@ -2061,16 +2059,15 @@ unlock:
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/*
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* Skip the page for one of the following reasons: (1)
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* It is enqueued in the physical memory allocator's
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* cache/free page queues. However, it is not the
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* first page in a run of contiguous cache/free pages.
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* (This case rarely occurs because the scan is
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* performed in ascending order.) (2) It is not
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* reserved, and it is transitioning from free to
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* allocated. (Conversely, the transition from
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* allocated to free for managed pages is blocked by
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* the page lock.) (3) It is allocated but not
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* contained by an object and not wired, e.g.,
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* allocated by Xen's balloon driver.
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* free page queues. However, it is not the first
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* page in a run of contiguous free pages. (This case
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* rarely occurs because the scan is performed in
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* ascending order.) (2) It is not reserved, and it is
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* transitioning from free to allocated. (Conversely,
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* the transition from allocated to free for managed
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* pages is blocked by the page lock.) (3) It is
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* allocated but not contained by an object and not
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* wired, e.g., allocated by Xen's balloon driver.
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*/
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run_ext = 0;
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}
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@ -2282,11 +2279,11 @@ unlock:
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if (order < VM_NFREEORDER) {
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/*
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* The page is enqueued in the physical memory
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* allocator's cache/free page queues.
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* Moreover, it is the first page in a power-
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* of-two-sized run of contiguous cache/free
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* pages. Jump ahead to the last page within
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* that run, and continue from there.
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* allocator's free page queues. Moreover, it
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* is the first page in a power-of-two-sized
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* run of contiguous free pages. Jump ahead
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* to the last page within that run, and
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* continue from there.
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*/
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m += (1 << order) - 1;
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}
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@ -2334,9 +2331,9 @@ CTASSERT(powerof2(NRUNS));
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* conditions by relocating the virtual pages using that physical memory.
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* Returns true if reclamation is successful and false otherwise. Since
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* relocation requires the allocation of physical pages, reclamation may
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* fail due to a shortage of cache/free pages. When reclamation fails,
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* callers are expected to perform VM_WAIT before retrying a failed
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* allocation operation, e.g., vm_page_alloc_contig().
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* fail due to a shortage of free pages. When reclamation fails, callers
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* are expected to perform VM_WAIT before retrying a failed allocation
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* operation, e.g., vm_page_alloc_contig().
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*
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* The caller must always specify an allocation class through "req".
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*
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@ -2371,8 +2368,8 @@ vm_page_reclaim_contig(int req, u_long npages, vm_paddr_t low, vm_paddr_t high,
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req_class = VM_ALLOC_SYSTEM;
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/*
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* Return if the number of cached and free pages cannot satisfy the
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* requested allocation.
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* Return if the number of free pages cannot satisfy the requested
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* allocation.
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*/
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count = vm_cnt.v_free_count;
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if (count < npages + vm_cnt.v_free_reserved || (count < npages +
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@ -2642,9 +2639,8 @@ vm_page_activate(vm_page_t m)
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/*
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* vm_page_free_wakeup:
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*
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* Helper routine for vm_page_free_toq() and vm_page_cache(). This
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* routine is called when a page has been added to the cache or free
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* queues.
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* Helper routine for vm_page_free_toq(). This routine is called
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* when a page is added to the free queues.
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*
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* The page queues must be locked.
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*/
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@ -2732,8 +2728,8 @@ vm_page_free_toq(vm_page_t m)
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pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT);
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/*
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* Insert the page into the physical memory allocator's
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* cache/free page queues.
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* Insert the page into the physical memory allocator's free
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* page queues.
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*/
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mtx_lock(&vm_page_queue_free_mtx);
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vm_phys_freecnt_adj(m, 1);
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@ -2833,21 +2829,10 @@ vm_page_unwire(vm_page_t m, uint8_t queue)
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/*
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* Move the specified page to the inactive queue.
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*
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* Many pages placed on the inactive queue should actually go
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* into the cache, but it is difficult to figure out which. What
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* we do instead, if the inactive target is well met, is to put
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* clean pages at the head of the inactive queue instead of the tail.
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* This will cause them to be moved to the cache more quickly and
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* if not actively re-referenced, reclaimed more quickly. If we just
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* stick these pages at the end of the inactive queue, heavy filesystem
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* meta-data accesses can cause an unnecessary paging load on memory bound
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* processes. This optimization causes one-time-use metadata to be
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* reused more quickly.
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*
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* Normally noreuse is FALSE, resulting in LRU operation. noreuse is set
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* to TRUE if we want this page to be 'as if it were placed in the cache',
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* except without unmapping it from the process address space. In
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* practice this is implemented by inserting the page at the head of the
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* Normally, "noreuse" is FALSE, resulting in LRU ordering of the inactive
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* queue. However, setting "noreuse" to TRUE will accelerate the specified
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* page's reclamation, but it will not unmap the page from any address space.
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* This is implemented by inserting the page near the head of the inactive
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* queue, using a marker page to guide FIFO insertion ordering.
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*
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* The page must be locked.
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@ -2974,16 +2959,9 @@ vm_page_advise(vm_page_t m, int advice)
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if (advice == MADV_FREE)
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/*
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* Mark the page clean. This will allow the page to be freed
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* up by the system. However, such pages are often reused
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* quickly by malloc() so we do not do anything that would
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* cause a page fault if we can help it.
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*
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* Specifically, we do not try to actually free the page now
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* nor do we try to put it in the cache (which would cause a
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* page fault on reuse).
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*
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* But we do make the page as freeable as we can without
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* actually taking the step of unmapping it.
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* without first paging it out. MADV_FREE pages are often
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* quickly reused by malloc(3), so we do not do anything that
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* would result in a page fault on a later access.
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*/
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vm_page_undirty(m);
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else if (advice != MADV_DONTNEED)
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@ -352,19 +352,16 @@ extern struct mtx_padalign pa_lock[];
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* free
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* Available for allocation now.
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*
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* cache
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* Almost available for allocation. Still associated with
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* an object, but clean and immediately freeable.
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*
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* The following lists are LRU sorted:
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*
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* inactive
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* Low activity, candidates for reclamation.
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* This list is approximately LRU ordered.
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*
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* laundry
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* This is the list of pages that should be
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* paged out next.
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*
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* active
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* Pages that are "active" i.e. they have been
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* Pages that are "active", i.e., they have been
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* recently referenced.
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*
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*/
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@ -62,7 +62,7 @@ __FBSDID("$FreeBSD$");
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/*
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* The reservation system supports the speculative allocation of large physical
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* pages ("superpages"). Speculative allocation enables the fully-automatic
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* pages ("superpages"). Speculative allocation enables the fully automatic
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* utilization of superpages by the virtual memory system. In other words, no
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* programmatic directives are required to use superpages.
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*/
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@ -155,11 +155,11 @@ popmap_is_set(popmap_t popmap[], int i)
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* physical pages for the range [pindex, pindex + VM_LEVEL_0_NPAGES) of offsets
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* within that object. The reservation's "popcnt" tracks the number of these
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* small physical pages that are in use at any given time. When and if the
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* reservation is not fully utilized, it appears in the queue of partially-
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* reservation is not fully utilized, it appears in the queue of partially
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* populated reservations. The reservation always appears on the containing
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* object's list of reservations.
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*
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* A partially-populated reservation can be broken and reclaimed at any time.
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* A partially populated reservation can be broken and reclaimed at any time.
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*/
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struct vm_reserv {
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TAILQ_ENTRY(vm_reserv) partpopq;
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@ -196,11 +196,11 @@ struct vm_reserv {
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static vm_reserv_t vm_reserv_array;
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/*
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* The partially-populated reservation queue
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* The partially populated reservation queue
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*
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* This queue enables the fast recovery of an unused cached or free small page
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* from a partially-populated reservation. The reservation at the head of
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* this queue is the least-recently-changed, partially-populated reservation.
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* This queue enables the fast recovery of an unused free small page from a
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* partially populated reservation. The reservation at the head of this queue
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* is the least recently changed, partially populated reservation.
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*
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* Access to this queue is synchronized by the free page queue lock.
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*/
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@ -225,7 +225,7 @@ SYSCTL_PROC(_vm_reserv, OID_AUTO, fullpop, CTLTYPE_INT | CTLFLAG_RD, NULL, 0,
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static int sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS);
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SYSCTL_OID(_vm_reserv, OID_AUTO, partpopq, CTLTYPE_STRING | CTLFLAG_RD, NULL, 0,
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sysctl_vm_reserv_partpopq, "A", "Partially-populated reservation queues");
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sysctl_vm_reserv_partpopq, "A", "Partially populated reservation queues");
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static long vm_reserv_reclaimed;
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SYSCTL_LONG(_vm_reserv, OID_AUTO, reclaimed, CTLFLAG_RD,
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@ -267,7 +267,7 @@ sysctl_vm_reserv_fullpop(SYSCTL_HANDLER_ARGS)
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}
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/*
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* Describes the current state of the partially-populated reservation queue.
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* Describes the current state of the partially populated reservation queue.
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*/
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static int
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sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS)
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@ -301,7 +301,7 @@ sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS)
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/*
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* Reduces the given reservation's population count. If the population count
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* becomes zero, the reservation is destroyed. Additionally, moves the
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* reservation to the tail of the partially-populated reservation queue if the
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* reservation to the tail of the partially populated reservation queue if the
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* population count is non-zero.
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*
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* The free page queue lock must be held.
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@ -363,7 +363,7 @@ vm_reserv_has_pindex(vm_reserv_t rv, vm_pindex_t pindex)
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/*
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* Increases the given reservation's population count. Moves the reservation
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* to the tail of the partially-populated reservation queue.
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* to the tail of the partially populated reservation queue.
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*
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* The free page queue must be locked.
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*/
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@ -597,7 +597,7 @@ found:
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}
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/*
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* Allocates a page from an existing or newly-created reservation.
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* Allocates a page from an existing or newly created reservation.
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*
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* The page "mpred" must immediately precede the offset "pindex" within the
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* specified object.
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@ -721,12 +721,12 @@ found:
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}
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/*
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* Breaks the given reservation. Except for the specified cached or free
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* page, all cached and free pages in the reservation are returned to the
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* physical memory allocator. The reservation's population count and map are
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* reset to their initial state.
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* Breaks the given reservation. Except for the specified free page, all free
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* pages in the reservation are returned to the physical memory allocator.
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* The reservation's population count and map are reset to their initial
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* state.
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*
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* The given reservation must not be in the partially-populated reservation
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* The given reservation must not be in the partially populated reservation
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* queue. The free page queue lock must be held.
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*/
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static void
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@ -895,7 +895,7 @@ vm_reserv_level(vm_page_t m)
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}
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/*
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* Returns a reservation level if the given page belongs to a fully-populated
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* Returns a reservation level if the given page belongs to a fully populated
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* reservation and -1 otherwise.
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*/
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int
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@ -908,8 +908,8 @@ vm_reserv_level_iffullpop(vm_page_t m)
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}
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/*
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* Breaks the given partially-populated reservation, releasing its cached and
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* free pages to the physical memory allocator.
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* Breaks the given partially populated reservation, releasing its free pages
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* to the physical memory allocator.
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*
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* The free page queue lock must be held.
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*/
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@ -927,9 +927,9 @@ vm_reserv_reclaim(vm_reserv_t rv)
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}
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/*
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* Breaks the reservation at the head of the partially-populated reservation
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* queue, releasing its cached and free pages to the physical memory
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* allocator. Returns TRUE if a reservation is broken and FALSE otherwise.
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* Breaks the reservation at the head of the partially populated reservation
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* queue, releasing its free pages to the physical memory allocator. Returns
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* TRUE if a reservation is broken and FALSE otherwise.
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*
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* The free page queue lock must be held.
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*/
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@ -947,11 +947,10 @@ vm_reserv_reclaim_inactive(void)
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}
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/*
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* Searches the partially-populated reservation queue for the least recently
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* active reservation with unused pages, i.e., cached or free, that satisfy the
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* given request for contiguous physical memory. If a satisfactory reservation
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* is found, it is broken. Returns TRUE if a reservation is broken and FALSE
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* otherwise.
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* Searches the partially populated reservation queue for the least recently
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* changed reservation with free pages that satisfy the given request for
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* contiguous physical memory. If a satisfactory reservation is found, it is
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* broken. Returns TRUE if a reservation is broken and FALSE otherwise.
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*
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* The free page queue lock must be held.
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*/
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