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| author | Ryan Stone <rstone@FreeBSD.org> | 2021-01-29 21:13:57 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2021-11-03 17:35:16 +0000 |
| commit | 8deb5f2f641581fc547710e9db04e5d784f374b9 (patch) | |
| tree | 7bc7590050a19947ea226e99e8362b10eb00e9f7 | |
| parent | 009b4d7190397032d21a7470ddf0cc93482297e2 (diff) | |
| download | src-8deb5f2f641581fc547710e9db04e5d784f374b9.tar.gz src-8deb5f2f641581fc547710e9db04e5d784f374b9.zip | |
Add a VM flag to prevent reclaim on a failed contig allocation
If a M_WAITOK contig alloc fails, the VM subsystem will try to
reclaim contiguous memory twice before actually failing the
request. On a system with 64GB of RAM I've observed this take
400-500ms before it finally gives up, and I believe that this
will only be worse on systems with even more memory.
In certain contexts this delay is extremely harmful, so add a flag
that will skip reclaim for allocation requests to allow those
paths to opt-out of doing an expensive reclaim.
Sponsored by: Dell Inc
Differential Revision: https://reviews.freebsd.org/D28422
Reviewed by: markj, kib
(cherry picked from commit 660344ca44c63bfe4a16c3e57d0f6dbcbb5e083e)
| -rw-r--r-- | sys/sys/malloc.h | 1 | ||||
| -rw-r--r-- | sys/vm/vm_kern.c | 9 | ||||
| -rw-r--r-- | sys/vm/vm_page.h | 3 |
3 files changed, 11 insertions, 2 deletions
diff --git a/sys/sys/malloc.h b/sys/sys/malloc.h index 93ec81c252ff..3d88460a751e 100644 --- a/sys/sys/malloc.h +++ b/sys/sys/malloc.h @@ -54,6 +54,7 @@ */ #define M_NOWAIT 0x0001 /* do not block */ #define M_WAITOK 0x0002 /* ok to block */ +#define M_NORECLAIM 0x0080 /* do not reclaim after failure */ #define M_ZERO 0x0100 /* bzero the allocation */ #define M_NOVM 0x0200 /* don't ask VM for pages */ #define M_USE_RESERVE 0x0400 /* can alloc out of reserve memory */ diff --git a/sys/vm/vm_kern.c b/sys/vm/vm_kern.c index f25784857440..7ab1fdb8950e 100644 --- a/sys/vm/vm_kern.c +++ b/sys/vm/vm_kern.c @@ -178,17 +178,22 @@ kmem_alloc_contig_pages(vm_object_t object, vm_pindex_t pindex, int domain, { vm_page_t m; int tries; - bool wait; + bool wait, reclaim; VM_OBJECT_ASSERT_WLOCKED(object); + /* Disallow an invalid combination of flags. */ + MPASS((pflags & (VM_ALLOC_WAITOK | VM_ALLOC_NORECLAIM)) != + (VM_ALLOC_WAITOK | VM_ALLOC_NORECLAIM)); + wait = (pflags & VM_ALLOC_WAITOK) != 0; + reclaim = (pflags & VM_ALLOC_NORECLAIM) == 0; pflags &= ~(VM_ALLOC_NOWAIT | VM_ALLOC_WAITOK | VM_ALLOC_WAITFAIL); pflags |= VM_ALLOC_NOWAIT; for (tries = wait ? 3 : 1;; tries--) { m = vm_page_alloc_contig_domain(object, pindex, domain, pflags, npages, low, high, alignment, boundary, memattr); - if (m != NULL || tries == 0) + if (m != NULL || tries == 0 || !reclaim) break; VM_OBJECT_WUNLOCK(object); diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h index d897a088244f..6e0a4328e260 100644 --- a/sys/vm/vm_page.h +++ b/sys/vm/vm_page.h @@ -541,6 +541,7 @@ vm_page_t PHYS_TO_VM_PAGE(vm_paddr_t pa); #define VM_ALLOC_WAITFAIL 0x0010 /* (acf) Sleep and return error */ #define VM_ALLOC_WIRED 0x0020 /* (acfgp) Allocate a wired page */ #define VM_ALLOC_ZERO 0x0040 /* (acfgp) Allocate a prezeroed page */ +#define VM_ALLOC_NORECLAIM 0x0080 /* (c) Do not reclaim after failure */ #define VM_ALLOC_NOOBJ 0x0100 /* (acg) No associated object */ #define VM_ALLOC_NOBUSY 0x0200 /* (acgp) Do not excl busy the page */ #define VM_ALLOC_NOCREAT 0x0400 /* (gp) Don't create a page */ @@ -570,6 +571,8 @@ malloc2vm_flags(int malloc_flags) pflags |= VM_ALLOC_NOWAIT; if ((malloc_flags & M_WAITOK)) pflags |= VM_ALLOC_WAITOK; + if ((malloc_flags & M_NORECLAIM)) + pflags |= VM_ALLOC_NORECLAIM; return (pflags); } #endif |