FreeBSD Bugzilla – Attachment 147286 Details for
Bug 187594
[zfs] [patch] ZFS ARC behavior problem and fix
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[patch]
Candidate Fix (supersedes previous)
patch-stable-10 (text/plain), 15.24 KB, created by
karl
on 2014-09-13 20:34:10 UTC
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Description:
Candidate Fix (supersedes previous)
Filename:
MIME Type:
Creator:
karl
Created:
2014-09-13 20:34:10 UTC
Size:
15.24 KB
patch
obsolete
>Index: sys/cddl/compat/opensolaris/kern/opensolaris_kmem.c >=================================================================== >--- sys/cddl/compat/opensolaris/kern/opensolaris_kmem.c (revision 271435) >+++ sys/cddl/compat/opensolaris/kern/opensolaris_kmem.c (working copy) >@@ -133,13 +133,6 @@ > return (kmem_size_val); > } > >-uint64_t >-kmem_used(void) >-{ >- >- return (vmem_size(kmem_arena, VMEM_ALLOC)); >-} >- > static int > kmem_std_constructor(void *mem, int size __unused, void *private, int flags) > { >Index: sys/cddl/compat/opensolaris/sys/kmem.h >=================================================================== >--- sys/cddl/compat/opensolaris/sys/kmem.h (revision 271435) >+++ sys/cddl/compat/opensolaris/sys/kmem.h (working copy) >@@ -66,7 +66,6 @@ > void *zfs_kmem_alloc(size_t size, int kmflags); > void zfs_kmem_free(void *buf, size_t size); > uint64_t kmem_size(void); >-uint64_t kmem_used(void); > kmem_cache_t *kmem_cache_create(char *name, size_t bufsize, size_t align, > int (*constructor)(void *, void *, int), void (*destructor)(void *, void *), > void (*reclaim)(void *) __unused, void *private, vmem_t *vmp, int cflags); >@@ -78,6 +77,9 @@ > int kmem_debugging(void); > void *calloc(size_t n, size_t s); > >+#define freemem (cnt.v_free_count + cnt.v_cache_count) >+#define minfree cnt.v_free_min >+#define heap_arena kmem_arena > #define kmem_alloc(size, kmflags) zfs_kmem_alloc((size), (kmflags)) > #define kmem_zalloc(size, kmflags) zfs_kmem_alloc((size), (kmflags) | M_ZERO) > #define kmem_free(buf, size) zfs_kmem_free((buf), (size)) >Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c >=================================================================== >--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c (revision 271435) >+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c (working copy) >@@ -138,6 +138,7 @@ > #include <sys/sdt.h> > > #include <vm/vm_pageout.h> >+#include <machine/vmparam.h> > > #ifdef illumos > #ifndef _KERNEL >@@ -193,9 +194,6 @@ > */ > static boolean_t arc_warm; > >-/* >- * These tunables are for performance analysis. >- */ > uint64_t zfs_arc_max; > uint64_t zfs_arc_min; > uint64_t zfs_arc_meta_limit = 0; >@@ -204,7 +202,21 @@ > int zfs_arc_p_min_shift = 0; > int zfs_disable_dup_eviction = 0; > uint64_t zfs_arc_average_blocksize = 8 * 1024; /* 8KB */ >+u_int zfs_arc_free_target = (1 << 16); /* default before pagedaemon init only */ >+int zfs_arc_reclaim_cache_free = 1; > >+static int sysctl_vfs_zfs_arc_free_target(SYSCTL_HANDLER_ARGS); >+ >+#ifdef _KERNEL >+static void >+arc_free_target_init(void *unused __unused) >+{ >+ >+ zfs_arc_free_target = cnt.v_free_target; >+} >+SYSINIT(arc_free_target_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_ANY, >+ arc_free_target_init, NULL); >+ > TUNABLE_QUAD("vfs.zfs.arc_max", &zfs_arc_max); > TUNABLE_QUAD("vfs.zfs.arc_min", &zfs_arc_min); > TUNABLE_QUAD("vfs.zfs.arc_meta_limit", &zfs_arc_meta_limit); >@@ -217,7 +229,40 @@ > SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, arc_average_blocksize, CTLFLAG_RDTUN, > &zfs_arc_average_blocksize, 0, > "ARC average blocksize"); >+SYSCTL_INT(_vfs_zfs, OID_AUTO, arc_reclaim_cache_free, CTLFLAG_RWTUN, >+ &zfs_arc_reclaim_cache_free, 0, >+ "ARC treats cached pages as free blocksize"); >+/* >+ * We don't have a tunable for arc_free_target due to the dependency on >+ * pagedaemon initialisation. >+ */ >+SYSCTL_PROC(_vfs_zfs, OID_AUTO, arc_free_target, >+ CTLTYPE_UINT | CTLFLAG_MPSAFE | CTLFLAG_RW, 0, sizeof(u_int), >+ sysctl_vfs_zfs_arc_free_target, "IU", >+ "Desired number of free pages below which ARC triggers reclaim"); > >+static int >+sysctl_vfs_zfs_arc_free_target(SYSCTL_HANDLER_ARGS) >+{ >+ u_int val; >+ int err; >+ >+ val = zfs_arc_free_target; >+ err = sysctl_handle_int(oidp, &val, 0, req); >+ if (err != 0 || req->newptr == NULL) >+ return (err); >+ >+ if (val < minfree) >+ return (EINVAL); >+ if (val > cnt.v_page_count) >+ return (EINVAL); >+ >+ zfs_arc_free_target = val; >+ >+ return (0); >+} >+#endif >+ > /* > * Note that buffers can be in one of 6 states: > * ARC_anon - anonymous (discussed below) >@@ -2421,6 +2466,7 @@ > void > arc_shrink(void) > { >+ > if (arc_c > arc_c_min) { > uint64_t to_free; > >@@ -2429,6 +2475,9 @@ > #else > to_free = arc_c >> arc_shrink_shift; > #endif >+ DTRACE_PROBE4(arc__shrink, uint64_t, arc_c, uint64_t, >+ arc_c_min, uint64_t, arc_p, uint64_t, to_free); >+ > if (arc_c > arc_c_min + to_free) > atomic_add_64(&arc_c, -to_free); > else >@@ -2439,12 +2488,19 @@ > arc_c = MAX(arc_size, arc_c_min); > if (arc_p > arc_c) > arc_p = (arc_c >> 1); >+ >+ DTRACE_PROBE2(arc__shrunk, uint64_t, arc_c, uint64_t, >+ arc_p); >+ > ASSERT(arc_c >= arc_c_min); > ASSERT((int64_t)arc_p >= 0); > } > >- if (arc_size > arc_c) >+ if (arc_size > arc_c) { >+ DTRACE_PROBE2(arc__shrink_adjust, uint64_t, arc_size, >+ uint64_t, arc_c); > arc_adjust(); >+ } > } > > static int needfree = 0; >@@ -2452,18 +2508,36 @@ > static int > arc_reclaim_needed(void) > { >+ u_int fm; > > #ifdef _KERNEL > >- if (needfree) >+ if (arc_size <= arc_c_min) { >+ DTRACE_PROBE2(arc__reclaim_min, uint64_t, arc_size, >+ uint64_t, arc_c_min); >+ return (0); >+ } >+ >+ if (needfree) { >+ DTRACE_PROBE(arc__reclaim_needfree); > return (1); >+ } > > /* > * Cooperate with pagedaemon when it's time for it to scan > * and reclaim some pages. > */ >- if (vm_paging_needed()) >+ if (zfs_arc_reclaim_cache_free == 0) >+ fm = cnt.v_free_count; >+ else >+ fm = freemem; >+ >+ if (fm < zfs_arc_free_target) { >+ DTRACE_PROBE3(arc__reclaim_freemem, uint64_t, >+ fm, uint64_t, zfs_arc_free_target, >+ int, zfs_arc_reclaim_cache_free); > return (1); >+ } > > #ifdef sun > /* >@@ -2491,8 +2565,19 @@ > if (availrmem < swapfs_minfree + swapfs_reserve + extra) > return (1); > >-#if defined(__i386) > /* >+ * Check that we have enough availrmem that memory locking (e.g., via >+ * mlock(3C) or memcntl(2)) can still succeed. (pages_pp_maximum >+ * stores the number of pages that cannot be locked; when availrmem >+ * drops below pages_pp_maximum, page locking mechanisms such as >+ * page_pp_lock() will fail.) >+ */ >+ if (availrmem <= pages_pp_maximum) >+ return (1); >+ >+#endif /* sun */ >+#if defined(__i386) || !defined(UMA_MD_SMALL_ALLOC) >+ /* > * If we're on an i386 platform, it's possible that we'll exhaust the > * kernel heap space before we ever run out of available physical > * memory. Most checks of the size of the heap_area compare against >@@ -2503,32 +2588,49 @@ > * heap is allocated. (Or, in the calculation, if less than 1/4th is > * free) > */ >- if (btop(vmem_size(heap_arena, VMEM_FREE)) < >- (btop(vmem_size(heap_arena, VMEM_FREE | VMEM_ALLOC)) >> 2)) >+ if (vmem_size(heap_arena, VMEM_FREE) < >+ (vmem_size(heap_arena, VMEM_FREE | VMEM_ALLOC) >> 2)) { >+ DTRACE_PROBE2(arc__reclaim_used, uint64_t, >+ vmem_size(heap_arena, VMEM_FREE), uint64_t, >+ (vmem_size(heap_arena, VMEM_FREE | VMEM_ALLOC)) >> 2); > return (1); >+ } > #endif >-#else /* !sun */ >- if (kmem_used() > (kmem_size() * 3) / 4) >+#ifdef sun >+ /* >+ * If zio data pages are being allocated out of a separate heap segment, >+ * then enforce that the size of available vmem for this arena remains >+ * above about 1/16th free. >+ * >+ * Note: The 1/16th arena free requirement was put in place >+ * to aggressively evict memory from the arc in order to avoid >+ * memory fragmentation issues. >+ */ >+ if (zio_arena != NULL && >+ vmem_size(zio_arena, VMEM_FREE) < >+ (vmem_size(zio_arena, VMEM_ALLOC) >> 4)) > return (1); > #endif /* sun */ >- >-#else >+#else /* _KERNEL */ > if (spa_get_random(100) == 0) > return (1); >-#endif >+#endif /* _KERNEL */ >+ DTRACE_PROBE(arc__reclaim_no); >+ > return (0); > } > > extern kmem_cache_t *zio_buf_cache[]; > extern kmem_cache_t *zio_data_buf_cache[]; > >-static void >+static void __used > arc_kmem_reap_now(arc_reclaim_strategy_t strat) > { > size_t i; > kmem_cache_t *prev_cache = NULL; > kmem_cache_t *prev_data_cache = NULL; > >+ DTRACE_PROBE(arc__kmem_reap_start); > #ifdef _KERNEL > if (arc_meta_used >= arc_meta_limit) { > /* >@@ -2564,6 +2666,16 @@ > } > kmem_cache_reap_now(buf_cache); > kmem_cache_reap_now(hdr_cache); >+ >+#ifdef sun >+ /* >+ * Ask the vmem areana to reclaim unused memory from its >+ * quantum caches. >+ */ >+ if (zio_arena != NULL && strat == ARC_RECLAIM_AGGR) >+ vmem_qcache_reap(zio_arena); >+#endif >+ DTRACE_PROBE(arc__kmem_reap_end); > } > > static void >@@ -2581,6 +2693,7 @@ > > if (arc_no_grow) { > if (last_reclaim == ARC_RECLAIM_CONS) { >+ DTRACE_PROBE(arc__reclaim_aggr_no_grow); > last_reclaim = ARC_RECLAIM_AGGR; > } else { > last_reclaim = ARC_RECLAIM_CONS; >@@ -2588,6 +2701,7 @@ > } else { > arc_no_grow = TRUE; > last_reclaim = ARC_RECLAIM_AGGR; >+ DTRACE_PROBE(arc__reclaim_aggr); > membar_producer(); > } > >@@ -2602,6 +2716,7 @@ > */ > arc_no_grow = TRUE; > last_reclaim = ARC_RECLAIM_AGGR; >+ DTRACE_PROBE(arc__reclaim_aggr_needfree); > } > arc_kmem_reap_now(last_reclaim); > arc_warm = B_TRUE; >@@ -2618,6 +2733,7 @@ > #ifdef _KERNEL > if (needfree) { > needfree = 0; >+ DTRACE_PROBE(arc__clear_needfree); > wakeup(&needfree); > } > #endif >@@ -2692,6 +2808,7 @@ > * cache size, increment the target cache size > */ > if (arc_size > arc_c - (2ULL << SPA_MAXBLOCKSHIFT)) { >+ DTRACE_PROBE1(arc__inc_adapt, int, bytes); > atomic_add_64(&arc_c, (int64_t)bytes); > if (arc_c > arc_c_max) > arc_c = arc_c_max; >@@ -2713,20 +2830,6 @@ > if (type == ARC_BUFC_METADATA && arc_meta_used >= arc_meta_limit) > return (1); > >-#ifdef sun >-#ifdef _KERNEL >- /* >- * If zio data pages are being allocated out of a separate heap segment, >- * then enforce that the size of available vmem for this area remains >- * above about 1/32nd free. >- */ >- if (type == ARC_BUFC_DATA && zio_arena != NULL && >- vmem_size(zio_arena, VMEM_FREE) < >- (vmem_size(zio_arena, VMEM_ALLOC) >> 5)) >- return (1); >-#endif >-#endif /* sun */ >- > if (arc_reclaim_needed()) > return (1); > >@@ -3885,20 +3988,16 @@ > arc_memory_throttle(uint64_t reserve, uint64_t txg) > { > #ifdef _KERNEL >- uint64_t available_memory = >- ptoa((uintmax_t)cnt.v_free_count + cnt.v_cache_count); >+ uint64_t available_memory = ptob(freemem); > static uint64_t page_load = 0; > static uint64_t last_txg = 0; > >-#ifdef sun >-#if defined(__i386) >+#if defined(__i386) || !defined(UMA_MD_SMALL_ALLOC) > available_memory = >- MIN(available_memory, vmem_size(heap_arena, VMEM_FREE)); >+ MIN(available_memory, ptob(vmem_size(heap_arena, VMEM_FREE))); > #endif >-#endif /* sun */ > >- if (cnt.v_free_count + cnt.v_cache_count > >- (uint64_t)physmem * arc_lotsfree_percent / 100) >+ if (freemem > (uint64_t)physmem * arc_lotsfree_percent / 100) > return (0); > > if (txg > last_txg) { >@@ -3911,7 +4010,7 @@ > * continue to let page writes occur as quickly as possible. > */ > if (curproc == pageproc) { >- if (page_load > available_memory / 4) >+ if (page_load > MAX(ptob(minfree), available_memory) / 4) > return (SET_ERROR(ERESTART)); > /* Note: reserve is inflated, so we deflate */ > page_load += reserve / 8; >@@ -3939,8 +4038,10 @@ > int error; > uint64_t anon_size; > >- if (reserve > arc_c/4 && !arc_no_grow) >+ if (reserve > arc_c/4 && !arc_no_grow) { > arc_c = MIN(arc_c_max, reserve * 4); >+ DTRACE_PROBE1(arc__set_reserve, uint64_t, arc_c); >+ } > if (reserve > arc_c) > return (SET_ERROR(ENOMEM)); > >@@ -3994,6 +4095,7 @@ > mutex_enter(&arc_lowmem_lock); > mutex_enter(&arc_reclaim_thr_lock); > needfree = 1; >+ DTRACE_PROBE(arc__needfree); > cv_signal(&arc_reclaim_thr_cv); > > /* >Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c >=================================================================== >--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c (revision 271435) >+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_tx.c (working copy) >@@ -1275,6 +1275,27 @@ > txg_how == TXG_WAITED); > ASSERT(!dsl_pool_sync_context(tx->tx_pool)); > >+#ifdef _KERNEL >+ /* >+ * First check to see if dirty_data_max needs adjusting. Do not allow >+ * the dirty data amount per pool to exceed free, non-swappable RAM. >+ * Subject this to the original test of the max_max limit and a >+ * minimum of 16MB. Necessary on FreeBSD due to ARC being allowed >+ * to pressure the VM system so as to prevent the acquisition of >+ * dirty I/O buffers from causing the zfs_io threads to wait on >+ * the pagedaemon for an allocation. >+ */ >+ >+ zfs_dirty_data_max = ptob(cnt.v_free_count) - ptob(cnt.v_free_min); >+ if (zfs_dirty_data_max <= 1 << 24) { >+ zfs_dirty_data_max = 1 << 24; >+ } >+ zfs_dirty_data_max = MIN(zfs_dirty_data_max, ptob(physmem) * >+ zfs_dirty_data_max_percent / 100); >+ zfs_dirty_data_max = MIN(zfs_dirty_data_max, zfs_dirty_data_max_max); >+#endif /* _KERNEL */ >+ >+ > /* If we might wait, we must not hold the config lock. */ > ASSERT(txg_how != TXG_WAIT || !dsl_pool_config_held(tx->tx_pool)); > >Index: sys/vm/vm_pageout.c >=================================================================== >--- sys/vm/vm_pageout.c (revision 271435) >+++ sys/vm/vm_pageout.c (working copy) >@@ -76,6 +76,7 @@ > __FBSDID("$FreeBSD$"); > > #include "opt_vm.h" >+#include "opt_kdtrace.h" > #include <sys/param.h> > #include <sys/systm.h> > #include <sys/kernel.h> >@@ -89,6 +90,7 @@ > #include <sys/racct.h> > #include <sys/resourcevar.h> > #include <sys/sched.h> >+#include <sys/sdt.h> > #include <sys/signalvar.h> > #include <sys/smp.h> > #include <sys/vnode.h> >@@ -115,10 +117,14 @@ > > /* the kernel process "vm_pageout"*/ > static void vm_pageout(void); >+static void vm_pageout_init(void); > static int vm_pageout_clean(vm_page_t); > static void vm_pageout_scan(struct vm_domain *vmd, int pass); > static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass); > >+SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init, >+ NULL); >+ > struct proc *pageproc; > > static struct kproc_desc page_kp = { >@@ -126,9 +132,13 @@ > vm_pageout, > &pageproc > }; >-SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, >+SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, > &page_kp); > >+SDT_PROVIDER_DEFINE(vm); >+SDT_PROBE_DEFINE(vm, , , vm__lowmem_cache); >+SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan); >+ > #if !defined(NO_SWAPPING) > /* the kernel process "vm_daemon"*/ > static void vm_daemon(void); >@@ -663,6 +673,7 @@ > * may acquire locks and/or sleep, so they can only be invoked > * when "tries" is greater than zero. > */ >+ SDT_PROBE0(vm, , , vm__lowmem_cache); > EVENTHANDLER_INVOKE(vm_lowmem, 0); > > /* >@@ -904,7 +915,7 @@ > * pass 1 - Move inactive to cache or free > * pass 2 - Launder dirty pages > */ >-static void >+static void __used > vm_pageout_scan(struct vm_domain *vmd, int pass) > { > vm_page_t m, next; >@@ -925,6 +936,7 @@ > /* > * Decrease registered cache sizes. > */ >+ SDT_PROBE0(vm, , , vm__lowmem_scan); > EVENTHANDLER_INVOKE(vm_lowmem, 0); > /* > * We do this explicitly after the caches have been >@@ -1650,15 +1662,11 @@ > } > > /* >- * vm_pageout is the high level pageout daemon. >+ * vm_pageout_init initialises basic pageout daemon settings. > */ > static void >-vm_pageout(void) >+vm_pageout_init(void) > { >-#if MAXMEMDOM > 1 >- int error, i; >-#endif >- > /* > * Initialize some paging parameters. > */ >@@ -1704,7 +1712,18 @@ > /* XXX does not really belong here */ > if (vm_page_max_wired == 0) > vm_page_max_wired = cnt.v_free_count / 3; >+} > >+/* >+ * vm_pageout is the high level pageout daemon. >+ */ >+static void >+vm_pageout(void) >+{ >+#if MAXMEMDOM > 1 >+ int error, i; >+#endif >+ > swap_pager_swap_init(); > #if MAXMEMDOM > 1 > for (i = 1; i < vm_ndomains; i++) {
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