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Request a CPU private mapping from sf_buf_alloc(). If the swap-backed

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memory disk is larger than the number of available sf_bufs, this improves
performance on SMPs by eliminating interprocessor TLB shootdowns.  For
example, with 6656 sf_bufs, the default on my test machine, and a 256MB
swap-backed memory disk, I see the command
"dd if=/dev/md0 of=/dev/null bs=64k" achieve ~489MB/sec with the default,
shared mappings, and ~587MB/sec with CPU private mappings.
This commit is contained in:
alc 2005-02-13 21:51:50 +00:00
parent 4f2d08a331
commit 13e88b41ba
1 changed files with 6 additions and 1 deletions
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7
sys/dev/md/md.c
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@ -552,13 +552,15 @@ mdstart_swap(struct md_s *sc, struct bio *bp)
m = vm_page_grab(sc->object, i,
VM_ALLOC_NORMAL|VM_ALLOC_RETRY);
VM_OBJECT_UNLOCK(sc->object);
sf = sf_buf_alloc(m, 0);
sched_pin();
sf = sf_buf_alloc(m, SFB_CPUPRIVATE);
VM_OBJECT_LOCK(sc->object);
if (bp->bio_cmd == BIO_READ) {
if (m->valid != VM_PAGE_BITS_ALL)
rv = vm_pager_get_pages(sc->object, &m, 1, 0);
if (rv == VM_PAGER_ERROR) {
sf_buf_free(sf);
sched_unpin();
vm_page_lock_queues();
vm_page_wakeup(m);
vm_page_unlock_queues();
@ -570,6 +572,7 @@ mdstart_swap(struct md_s *sc, struct bio *bp)
rv = vm_pager_get_pages(sc->object, &m, 1, 0);
if (rv == VM_PAGER_ERROR) {
sf_buf_free(sf);
sched_unpin();
vm_page_lock_queues();
vm_page_wakeup(m);
vm_page_unlock_queues();
@ -583,6 +586,7 @@ mdstart_swap(struct md_s *sc, struct bio *bp)
rv = vm_pager_get_pages(sc->object, &m, 1, 0);
if (rv == VM_PAGER_ERROR) {
sf_buf_free(sf);
sched_unpin();
vm_page_lock_queues();
vm_page_wakeup(m);
vm_page_unlock_queues();
@ -594,6 +598,7 @@ mdstart_swap(struct md_s *sc, struct bio *bp)
#endif
}
sf_buf_free(sf);
sched_unpin();
vm_page_lock_queues();
vm_page_wakeup(m);
vm_page_activate(m);