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Based on work posted at https://reviews.freebsd.org/D13484, change

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swap_pager_swapoff_object and swp_pager_force_pagein so that they can
page in multiple pages at a time to a swap device, rather than doing
one I/O operation for each page.

Tested by: pho
Submitted by: ota_j.email.ne.jp (Yoshihiro Ota)
Reviewed by: alc, markj, kib
Approved by: kib, markj (mentors)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D20635
This commit is contained in:
dougm 2019-07-05 16:49:34 +00:00
parent 93d0ca1e9d
commit d707ae5ef8
1 changed files with 83 additions and 35 deletions
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118
sys/vm/swap_pager.c
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@ -1662,6 +1662,7 @@ swp_pager_force_dirty(vm_page_t m)
vm_page_unlock(m);
#endif
vm_page_xunbusy(m);
swap_pager_unswapped(m);
}
static void
@ -1673,69 +1674,116 @@ swp_pager_force_launder(vm_page_t m)
vm_page_launder(m);
vm_page_unlock(m);
vm_page_xunbusy(m);
swap_pager_unswapped(m);
}
/*
* SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in
* SWP_PAGER_FORCE_PAGEIN() - force swap blocks to be paged in
*
* This routine dissociates the page at the given index within an object
* from its backing store, paging it in if it does not reside in memory.
* If the page is paged in, it is marked dirty and placed in the laundry
* queue. The page is marked dirty because it no longer has backing
* store. It is placed in the laundry queue because it has not been
* accessed recently. Otherwise, it would already reside in memory.
*
* We also attempt to swap in all other pages in the swap block.
* However, we only guarantee that the one at the specified index is
* paged in.
*
* XXX - The code to page the whole block in doesn't work, so we
* revert to the one-by-one behavior for now. Sigh.
* This routine dissociates pages starting at the given index within an
* object from their backing store, paging them in if they do not reside
* in memory. Pages that are paged in are marked dirty and placed in the
* laundry queue. Pages are marked dirty because they no longer have
* backing store. They are placed in the laundry queue because they have
* not been accessed recently. Otherwise, they would already reside in
* memory.
*/
static void
swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex)
swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex, int npages)
{
vm_page_t m;
vm_page_t ma[npages];
int i, j;
vm_object_pip_add(object, 1);
m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
if (m->valid == VM_PAGE_BITS_ALL) {
vm_object_pip_wakeup(object);
swp_pager_force_dirty(m);
vm_pager_page_unswapped(m);
return;
KASSERT(npages > 0, ("%s: No pages", __func__));
KASSERT(npages <= MAXPHYS / PAGE_SIZE,
("%s: Too many pages: %d", __func__, npages));
vm_object_pip_add(object, npages);
vm_page_grab_pages(object, pindex, VM_ALLOC_NORMAL, ma, npages);
for (i = j = 0;; i++) {
/* Count nonresident pages, to page-in all at once. */
if (i < npages && ma[i]->valid != VM_PAGE_BITS_ALL)
continue;
if (j < i) {
/* Page-in nonresident pages. Mark for laundering. */
if (swap_pager_getpages(object, &ma[j], i - j, NULL,
NULL) != VM_PAGER_OK)
panic("%s: read from swap failed", __func__);
do {
swp_pager_force_launder(ma[j]);
} while (++j < i);
}
if (i == npages)
break;
/* Mark dirty a resident page. */
swp_pager_force_dirty(ma[j++]);
}
if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK)
panic("swap_pager_force_pagein: read from swap failed");/*XXX*/
vm_object_pip_wakeup(object);
swp_pager_force_launder(m);
vm_pager_page_unswapped(m);
vm_object_pip_wakeupn(object, npages);
}
/*
* swap_pager_swapoff_object:
*
* Page in all of the pages that have been paged out for an object
* from a given swap device.
* to a swap device.
*/
static void
swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object)
{
struct swblk *sb;
vm_pindex_t pi;
vm_pindex_t pi, s_pindex;
daddr_t blk, n_blks, s_blk;
int i;
n_blks = 0;
for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE(
&object->un_pager.swp.swp_blks, pi)) != NULL; ) {
pi = sb->p + SWAP_META_PAGES;
for (i = 0; i < SWAP_META_PAGES; i++) {
if (sb->d[i] == SWAPBLK_NONE)
blk = sb->d[i];
if (!swp_pager_isondev(blk, sp))
blk = SWAPBLK_NONE;
/*
* If there are no blocks/pages accumulated, start a new
* accumulation here.
*/
if (n_blks == 0) {
if (blk != SWAPBLK_NONE) {
s_blk = blk;
s_pindex = sb->p + i;
n_blks = 1;
}
continue;
if (swp_pager_isondev(sb->d[i], sp))
swp_pager_force_pagein(object, sb->p + i);
}
/*
* If the accumulation can be extended without breaking
* the sequence of consecutive blocks and pages that
* swp_pager_force_pagein() depends on, do so.
*/
if (n_blks < MAXPHYS / PAGE_SIZE &&
s_blk + n_blks == blk &&
s_pindex + n_blks == sb->p + i) {
++n_blks;
continue;
}
/*
* The sequence of consecutive blocks and pages cannot
* be extended, so page them all in here. Then,
* because doing so involves releasing and reacquiring
* a lock that protects the swap block pctrie, do not
* rely on the current swap block. Break this loop and
* re-fetch the same pindex from the pctrie again.
*/
swp_pager_force_pagein(object, s_pindex, n_blks);
n_blks = 0;
break;
}
if (i == SWAP_META_PAGES)
pi = sb->p + SWAP_META_PAGES;
}
if (n_blks > 0)
swp_pager_force_pagein(object, s_pindex, n_blks);
}
/*