From patchwork Thu Jun 29 01:16:11 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: DJ Delorie X-Patchwork-Id: 21324 Received: (qmail 90921 invoked by alias); 29 Jun 2017 01:16:21 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 90900 invoked by uid 89); 29 Jun 2017 01:16:19 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-15.9 required=5.0 tests=BAYES_00, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_LAZY_DOMAIN_SECURITY, RP_MATCHES_RCVD, SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=H*r:8.14.7 X-HELO: mx1.redhat.com DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 80C1B6AAE8 Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=dj@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 80C1B6AAE8 From: DJ Delorie To: Siddhesh Poyarekar Cc: libc-alpha@sourceware.org, carlos@redhat.com, fweimer@redhat.com Subject: Re: [updated patch] malloc per-thread cache ready for review In-Reply-To: (message from Siddhesh Poyarekar on Wed, 28 Jun 2017 12:58:23 +0530) Date: Wed, 28 Jun 2017 21:16:11 -0400 Message-ID: MIME-Version: 1.0 Siddhesh Poyarekar writes: > haha, interesting, because I remember Florian and I had this discussion > about the utility of SXID_IGNORE six months ago when I designed the > scope control for the envvars. Lets have Florian explain this. Changed to SXID_ERASE. > The braces should be on the next line: Fixed. >>>> +static void __attribute__ ((section ("__libc_thread_freeres_fn"))) >>> >>> __attribute__ should be on its own line. >> >> Likewise, I was copying the formatting used elsewhere in malloc. What >> is the correct formatting for that line? Do I need to fix the other >> existing instances also? > > Sure, but in a separate (obvious) patch. The malloc code was in a > completely different format when it was ported in from dlmalloc and > since then it has been a bit of a mishmash that needs a cleanup. I scanned all of glibc, and the same-line syntax seems to be nearly ubiquitous, with only one example of it on a separate line. I couldn't find any mention of attributes in the GNU or GLIBC coding standards either... I'm certainly willing to do a global tweak patch later, but... is this documented somewhere? > Opening brace for the for loop should be on the next line and everything > else indented accordingly. Fixed. > However, I noticed that it is a function of a bunch of other macros > and unless those are constant across architectures it won't go into > tunables as is. They're different for 64-bit vs 32-bit at least. Tweaked patch attached. diff -x .git -x po -rup glibc.pristine/config.make.in glibc.djmalloc-tcache/config.make.in --- glibc.pristine/config.make.in 2017-06-20 12:54:22.636484566 -0400 +++ glibc.djmalloc-tcache/config.make.in 2017-06-26 17:32:41.164888977 -0400 @@ -78,6 +78,8 @@ multi-arch = @multi_arch@ mach-interface-list = @mach_interface_list@ +experimental-malloc = @experimental_malloc@ + nss-crypt = @libc_cv_nss_crypt@ static-nss-crypt = @libc_cv_static_nss_crypt@ diff -x .git -x po -rup glibc.pristine/configure glibc.djmalloc-tcache/configure --- glibc.pristine/configure 2017-06-20 12:54:22.637484566 -0400 +++ glibc.djmalloc-tcache/configure 2017-06-26 17:32:41.163888976 -0400 @@ -674,6 +674,7 @@ build_obsolete_nsl link_obsolete_rpc libc_cv_static_nss_crypt libc_cv_nss_crypt +experimental_malloc enable_werror all_warnings force_install @@ -779,6 +780,7 @@ enable_kernel enable_all_warnings enable_werror enable_multi_arch +enable_experimental_malloc enable_nss_crypt enable_obsolete_rpc enable_obsolete_nsl @@ -1450,6 +1452,8 @@ Optional Features: --disable-werror do not build with -Werror --enable-multi-arch enable single DSO with optimizations for multiple architectures + --disable-experimental-malloc + disable experimental malloc features --enable-nss-crypt enable libcrypt to use nss --enable-obsolete-rpc build and install the obsolete RPC code for link-time usage @@ -3522,6 +3526,15 @@ else fi +# Check whether --enable-experimental-malloc was given. +if test "${enable_experimental_malloc+set}" = set; then : + enableval=$enable_experimental_malloc; experimental_malloc=$enableval +else + experimental_malloc=yes +fi + + + # Check whether --enable-nss-crypt was given. if test "${enable_nss_crypt+set}" = set; then : enableval=$enable_nss_crypt; nss_crypt=$enableval diff -x .git -x po -rup glibc.pristine/configure.ac glibc.djmalloc-tcache/configure.ac --- glibc.pristine/configure.ac 2017-06-20 12:54:22.638484567 -0400 +++ glibc.djmalloc-tcache/configure.ac 2017-06-26 17:32:41.155888970 -0400 @@ -313,6 +313,13 @@ AC_ARG_ENABLE([multi-arch], [multi_arch=$enableval], [multi_arch=default]) +AC_ARG_ENABLE([experimental-malloc], + AC_HELP_STRING([--disable-experimental-malloc], + [disable experimental malloc features]), + [experimental_malloc=$enableval], + [experimental_malloc=yes]) +AC_SUBST(experimental_malloc) + AC_ARG_ENABLE([nss-crypt], AC_HELP_STRING([--enable-nss-crypt], [enable libcrypt to use nss]), diff -x .git -x po -rup glibc.pristine/elf/dl-tunables.list glibc.djmalloc-tcache/elf/dl-tunables.list --- glibc.pristine/elf/dl-tunables.list 2017-06-23 20:49:10.174148477 -0400 +++ glibc.djmalloc-tcache/elf/dl-tunables.list 2017-06-28 21:01:06.748079482 -0400 @@ -76,6 +76,18 @@ glibc { minval: 1 security_level: SXID_IGNORE } + tcache_max { + type: SIZE_T + security_level: SXID_ERASE + } + tcache_count { + type: SIZE_T + security_level: SXID_ERASE + } + tcache_unsorted_limit { + type: SIZE_T + security_level: SXID_ERASE + } } tune { hwcap_mask { diff -x .git -x po -rup glibc.pristine/malloc/Makefile glibc.djmalloc-tcache/malloc/Makefile --- glibc.pristine/malloc/Makefile 2017-06-23 20:49:10.199148493 -0400 +++ glibc.djmalloc-tcache/malloc/Makefile 2017-06-26 17:32:41.153888968 -0400 @@ -189,6 +189,11 @@ tst-malloc-usable-static-ENV = $(tst-mal tst-malloc-usable-tunables-ENV = GLIBC_TUNABLES=glibc.malloc.check=3 tst-malloc-usable-static-tunables-ENV = $(tst-malloc-usable-tunables-ENV) +ifeq ($(experimental-malloc),yes) +CPPFLAGS-malloc.c += -DUSE_TCACHE=1 +else +CPPFLAGS-malloc.c += -DUSE_TCACHE=0 +endif # Uncomment this for test releases. For public releases it is too expensive. #CPPFLAGS-malloc.o += -DMALLOC_DEBUG=1 diff -x .git -x po -rup glibc.pristine/malloc/arena.c glibc.djmalloc-tcache/malloc/arena.c --- glibc.pristine/malloc/arena.c 2017-06-20 12:54:22.645484573 -0400 +++ glibc.djmalloc-tcache/malloc/arena.c 2017-06-26 17:49:33.701608305 -0400 @@ -236,6 +236,11 @@ TUNABLE_CALLBACK_FNDECL (set_perturb_byt TUNABLE_CALLBACK_FNDECL (set_trim_threshold, size_t) TUNABLE_CALLBACK_FNDECL (set_arena_max, size_t) TUNABLE_CALLBACK_FNDECL (set_arena_test, size_t) +#if USE_TCACHE +TUNABLE_CALLBACK_FNDECL (set_tcache_max, size_t) +TUNABLE_CALLBACK_FNDECL (set_tcache_count, size_t) +TUNABLE_CALLBACK_FNDECL (set_tcache_unsorted_limit, size_t) +#endif #else /* Initialization routine. */ #include @@ -322,6 +327,12 @@ ptmalloc_init (void) TUNABLE_GET (mmap_max, int32_t, TUNABLE_CALLBACK (set_mmaps_max)); TUNABLE_GET (arena_max, size_t, TUNABLE_CALLBACK (set_arena_max)); TUNABLE_GET (arena_test, size_t, TUNABLE_CALLBACK (set_arena_test)); +#if USE_TCACHE + TUNABLE_GET (tcache_max, size_t, TUNABLE_CALLBACK (set_tcache_max)); + TUNABLE_GET (tcache_count, size_t, TUNABLE_CALLBACK (set_tcache_count)); + TUNABLE_GET (tcache_unsorted_limit, size_t, + TUNABLE_CALLBACK (set_tcache_unsorted_limit)); +#endif __libc_lock_unlock (main_arena.mutex); #else const char *s = NULL; diff -x .git -x po -rup glibc.pristine/malloc/malloc.c glibc.djmalloc-tcache/malloc/malloc.c --- glibc.pristine/malloc/malloc.c 2017-05-03 16:26:47.559839224 -0400 +++ glibc.djmalloc-tcache/malloc/malloc.c 2017-06-28 21:02:22.059151815 -0400 @@ -296,6 +296,30 @@ __malloc_assert (const char *assertion, } #endif +#if USE_TCACHE +/* We want 64 entries. This is an arbitrary limit, which tunables can reduce. */ +# define TCACHE_MAX_BINS 64 +# define MAX_TCACHE_SIZE tidx2usize (TCACHE_MAX_BINS-1) + +/* Only used to pre-fill the tunables. */ +# define tidx2usize(idx) (((size_t) idx) * MALLOC_ALIGNMENT + MINSIZE - SIZE_SZ) + +/* When "x" is from chunksize(). */ +# define csize2tidx(x) (((x) - MINSIZE + MALLOC_ALIGNMENT - 1) / MALLOC_ALIGNMENT) +/* When "x" is a user-provided size. */ +# define usize2tidx(x) csize2tidx (request2size (x)) + +/* With rounding and alignment, the bins are... + idx 0 bytes 0..24 (64-bit) or 0..12 (32-bit) + idx 1 bytes 25..40 or 13..20 + idx 2 bytes 41..56 or 21..28 + etc. */ + +/* This is another arbitrary limit, which tunables can change. Each + tcache bin will hold at most this number of chunks. */ +# define TCACHE_FILL_COUNT 7 +#endif + /* REALLOC_ZERO_BYTES_FREES should be set if a call to @@ -1712,6 +1736,17 @@ struct malloc_par /* First address handed out by MORECORE/sbrk. */ char *sbrk_base; + +#if USE_TCACHE + /* Maximum number of buckets to use. */ + size_t tcache_bins; + size_t tcache_max_bytes; + /* Maximum number of chunks in each bucket. */ + size_t tcache_count; + /* Maximum number of chunks to remove from the unsorted list, which + aren't used to prefill the cache. */ + size_t tcache_unsorted_limit; +#endif }; /* There are several instances of this struct ("arenas") in this @@ -1750,6 +1785,13 @@ static struct malloc_par mp_ = .trim_threshold = DEFAULT_TRIM_THRESHOLD, #define NARENAS_FROM_NCORES(n) ((n) * (sizeof (long) == 4 ? 2 : 8)) .arena_test = NARENAS_FROM_NCORES (1) +#if USE_TCACHE + , + .tcache_count = TCACHE_FILL_COUNT, + .tcache_bins = TCACHE_MAX_BINS, + .tcache_max_bytes = tidx2usize (TCACHE_MAX_BINS-1), + .tcache_unsorted_limit = 0 /* No limit. */ +#endif }; /* Maximum size of memory handled in fastbins. */ @@ -2875,6 +2917,124 @@ mremap_chunk (mchunkptr p, size_t new_si /*------------------------ Public wrappers. --------------------------------*/ +#if USE_TCACHE + +/* We overlay this structure on the user-data portion of a chunk when + the chunk is stored in the per-thread cache. */ +typedef struct tcache_entry +{ + struct tcache_entry *next; +} tcache_entry; + +/* There is one of these for each thread, which contains the + per-thread cache (hence "tcache_perthread_struct"). Keeping + overall size low is mildly important. Note that COUNTS and ENTRIES + are redundant (we could have just counted the linked list each + time), this is for performance reasons. */ +typedef struct tcache_perthread_struct +{ + char counts[TCACHE_MAX_BINS]; + tcache_entry *entries[TCACHE_MAX_BINS]; +} tcache_perthread_struct; + +static __thread char tcache_shutting_down = 0; +static __thread tcache_perthread_struct *tcache = NULL; + +/* Caller must ensure that we know tc_idx is valid and there's room + for more chunks. */ +static void +tcache_put (mchunkptr chunk, size_t tc_idx) +{ + tcache_entry *e = (tcache_entry *) chunk2mem (chunk); + assert (tc_idx < TCACHE_MAX_BINS); + e->next = tcache->entries[tc_idx]; + tcache->entries[tc_idx] = e; + ++(tcache->counts[tc_idx]); +} + +/* Caller must ensure that we know tc_idx is valid and there's + available chunks to remove. */ +static void * +tcache_get (size_t tc_idx) +{ + tcache_entry *e = tcache->entries[tc_idx]; + assert (tc_idx < TCACHE_MAX_BINS); + assert (tcache->entries[tc_idx] > 0); + tcache->entries[tc_idx] = e->next; + --(tcache->counts[tc_idx]); + return (void *) e; +} + +static void __attribute__ ((section ("__libc_thread_freeres_fn"))) +tcache_thread_freeres (void) +{ + int i; + tcache_perthread_struct *tcache_tmp = tcache; + + if (!tcache) + return; + + tcache = NULL; + + for (i = 0; i < TCACHE_MAX_BINS; ++i) + { + while (tcache_tmp->entries[i]) + { + tcache_entry *e = tcache_tmp->entries[i]; + tcache_tmp->entries[i] = e->next; + __libc_free (e); + } + } + + __libc_free (tcache_tmp); + + tcache_shutting_down = 1; +} +text_set_element (__libc_thread_subfreeres, tcache_thread_freeres); + +static void +tcache_init(void) +{ + mstate ar_ptr; + void *victim = 0; + const size_t bytes = sizeof (tcache_perthread_struct); + + if (tcache_shutting_down) + return; + + arena_get (ar_ptr, bytes); + victim = _int_malloc (ar_ptr, bytes); + if (!victim && ar_ptr != NULL) + { + ar_ptr = arena_get_retry (ar_ptr, bytes); + victim = _int_malloc (ar_ptr, bytes); + } + + + if (ar_ptr != NULL) + __libc_lock_unlock (ar_ptr->mutex); + + /* In a low memory situation, we may not be able to allocate memory + - in which case, we just keep trying later. However, we + typically do this very early, so either there is sufficient + memory, or there isn't enough memory to do non-trivial + allocations anyway. */ + if (victim) + { + tcache = (tcache_perthread_struct *) victim; + memset (tcache, 0, sizeof (tcache_perthread_struct)); + } + +} + +#define MAYBE_INIT_TCACHE() \ + if (__glibc_unlikely (tcache == NULL)) \ + tcache_init(); + +#else +#define MAYBE_INIT_TCACHE() +#endif + void * __libc_malloc (size_t bytes) { @@ -2885,6 +3045,21 @@ __libc_malloc (size_t bytes) = atomic_forced_read (__malloc_hook); if (__builtin_expect (hook != NULL, 0)) return (*hook)(bytes, RETURN_ADDRESS (0)); +#if USE_TCACHE + /* int_free also calls request2size, be careful to not pad twice. */ + size_t tbytes = request2size (bytes); + size_t tc_idx = csize2tidx (tbytes); + + MAYBE_INIT_TCACHE (); + + if (tc_idx < mp_.tcache_bins + && tc_idx < TCACHE_MAX_BINS /* to appease gcc */ + && tcache + && tcache->entries[tc_idx] != NULL) + { + return tcache_get (tc_idx); + } +#endif arena_get (ar_ptr, bytes); @@ -2944,6 +3119,8 @@ __libc_free (void *mem) return; } + MAYBE_INIT_TCACHE (); + ar_ptr = arena_for_chunk (p); _int_free (ar_ptr, p, 0); } @@ -2981,7 +3158,10 @@ __libc_realloc (void *oldmem, size_t byt if (chunk_is_mmapped (oldp)) ar_ptr = NULL; else - ar_ptr = arena_for_chunk (oldp); + { + MAYBE_INIT_TCACHE (); + ar_ptr = arena_for_chunk (oldp); + } /* Little security check which won't hurt performance: the allocator never wrapps around at the end of the address space. Therefore @@ -3206,6 +3386,8 @@ __libc_calloc (size_t n, size_t elem_siz sz = bytes; + MAYBE_INIT_TCACHE (); + arena_get (av, sz); if (av) { @@ -3336,6 +3518,10 @@ _int_malloc (mstate av, size_t bytes) mchunkptr fwd; /* misc temp for linking */ mchunkptr bck; /* misc temp for linking */ +#if USE_TCACHE + size_t tcache_unsorted_count; /* count of unsorted chunks processed */ +#endif + const char *errstr = NULL; /* @@ -3365,19 +3551,22 @@ _int_malloc (mstate av, size_t bytes) can try it without checking, which saves some time on this fast path. */ +#define REMOVE_FB(fb, victim, pp) \ + do \ + { \ + victim = pp; \ + if (victim == NULL) \ + break; \ + } \ + while ((pp = catomic_compare_and_exchange_val_acq (fb, victim->fd, victim)) \ + != victim); \ + if ((unsigned long) (nb) <= (unsigned long) (get_max_fast ())) { idx = fastbin_index (nb); mfastbinptr *fb = &fastbin (av, idx); mchunkptr pp = *fb; - do - { - victim = pp; - if (victim == NULL) - break; - } - while ((pp = catomic_compare_and_exchange_val_acq (fb, victim->fd, victim)) - != victim); + REMOVE_FB (fb, victim, pp); if (victim != 0) { if (__builtin_expect (fastbin_index (chunksize (victim)) != idx, 0)) @@ -3388,6 +3577,26 @@ _int_malloc (mstate av, size_t bytes) return NULL; } check_remalloced_chunk (av, victim, nb); +#if USE_TCACHE + /* While we're here, if we see other chunks of the same size, + stash them in the tcache. */ + size_t tc_idx = csize2tidx (nb); + if (tcache && tc_idx < mp_.tcache_bins) + { + mchunkptr tc_victim; + + /* While bin not empty and tcache not full, copy chunks over. */ + while (tcache->counts[tc_idx] < mp_.tcache_count + && (pp = *fb) != NULL) + { + REMOVE_FB (fb, tc_victim, pp); + if (tc_victim != 0) + { + tcache_put (tc_victim, tc_idx); + } + } + } +#endif void *p = chunk2mem (victim); alloc_perturb (p, bytes); return p; @@ -3426,6 +3635,32 @@ _int_malloc (mstate av, size_t bytes) if (av != &main_arena) set_non_main_arena (victim); check_malloced_chunk (av, victim, nb); +#if USE_TCACHE + /* While we're here, if we see other chunks of the same size, + stash them in the tcache. */ + size_t tc_idx = csize2tidx (nb); + if (tcache && tc_idx < mp_.tcache_bins) + { + mchunkptr tc_victim; + + /* While bin not empty and tcache not full, copy chunks over. */ + while (tcache->counts[tc_idx] < mp_.tcache_count + && (tc_victim = last (bin)) != bin) + { + if (tc_victim != 0) + { + bck = tc_victim->bk; + set_inuse_bit_at_offset (tc_victim, nb); + if (av != &main_arena) + set_non_main_arena (tc_victim); + bin->bk = bck; + bck->fd = bin; + + tcache_put (tc_victim, tc_idx); + } + } + } +#endif void *p = chunk2mem (victim); alloc_perturb (p, bytes); return p; @@ -3464,6 +3699,16 @@ _int_malloc (mstate av, size_t bytes) otherwise need to expand memory to service a "small" request. */ +#if USE_TCACHE + INTERNAL_SIZE_T tcache_nb = 0; + size_t tc_idx = csize2tidx (nb); + if (tcache && tc_idx < mp_.tcache_bins) + tcache_nb = nb; + int return_cached = 0; + + tcache_unsorted_count = 0; +#endif + for (;; ) { int iters = 0; @@ -3524,10 +3769,26 @@ _int_malloc (mstate av, size_t bytes) set_inuse_bit_at_offset (victim, size); if (av != &main_arena) set_non_main_arena (victim); +#if USE_TCACHE + /* Fill cache first, return to user only if cache fills. + We may return one of these chunks later. */ + if (tcache_nb + && tcache->counts[tc_idx] < mp_.tcache_count) + { + tcache_put (victim, tc_idx); + return_cached = 1; + continue; + } + else + { +#endif check_malloced_chunk (av, victim, nb); void *p = chunk2mem (victim); alloc_perturb (p, bytes); return p; +#if USE_TCACHE + } +#endif } /* place chunk in bin */ @@ -3594,11 +3855,31 @@ _int_malloc (mstate av, size_t bytes) fwd->bk = victim; bck->fd = victim; +#if USE_TCACHE + /* If we've processed as many chunks as we're allowed while + filling the cache, return one of the cached ones. */ + ++tcache_unsorted_count; + if (return_cached + && mp_.tcache_unsorted_limit > 0 + && tcache_unsorted_count > mp_.tcache_unsorted_limit) + { + return tcache_get (tc_idx); + } +#endif + #define MAX_ITERS 10000 if (++iters >= MAX_ITERS) break; } +#if USE_TCACHE + /* If all the small chunks we found ended up cached, return one now. */ + if (return_cached) + { + return tcache_get (tc_idx); + } +#endif + /* If a large request, scan through the chunks of current bin in sorted order to find smallest that fits. Use the skip list for this. @@ -3884,6 +4165,20 @@ _int_free (mstate av, mchunkptr p, int h check_inuse_chunk(av, p); +#if USE_TCACHE + { + size_t tc_idx = csize2tidx (size); + + if (tcache + && tc_idx < mp_.tcache_bins + && tcache->counts[tc_idx] < mp_.tcache_count) + { + tcache_put (p, tc_idx); + return; + } + } +#endif + /* If eligible, place chunk on a fastbin so it can be found and used quickly in malloc. @@ -4845,6 +5140,38 @@ do_set_arena_max (size_t value) return 1; } +#if USE_TCACHE +static inline int +__always_inline +do_set_tcache_max (size_t value) +{ + if (value >= 0 && value <= MAX_TCACHE_SIZE) + { + LIBC_PROBE (memory_tunable_tcache_max_bytes, 2, value, mp_.tcache_max_bytes); + mp_.tcache_max_bytes = value; + mp_.tcache_bins = csize2tidx (request2size(value)) + 1; + } + return 1; +} + +static inline int +__always_inline +do_set_tcache_count (size_t value) +{ + LIBC_PROBE (memory_tunable_tcache_count, 2, value, mp_.tcache_count); + mp_.tcache_count = value; + return 1; +} + +static inline int +__always_inline +do_set_tcache_unsorted_limit (size_t value) +{ + LIBC_PROBE (memory_tunable_tcache_unsorted_limit, 2, value, mp_.tcache_unsorted_limit); + mp_.tcache_unsorted_limit = value; + return 1; +} +#endif int __libc_mallopt (int param_number, int value) diff -x .git -x po -rup glibc.pristine/manual/probes.texi glibc.djmalloc-tcache/manual/probes.texi --- glibc.pristine/manual/probes.texi 2017-01-10 17:02:06.305343587 -0500 +++ glibc.djmalloc-tcache/manual/probes.texi 2017-06-26 17:32:35.785884967 -0400 @@ -231,6 +231,25 @@ dynamic brk/mmap thresholds. Argument @ the adjusted mmap and trim thresholds, respectively. @end deftp +@deftp Probe memory_tunable_tcache_max_bytes (int @var{$arg1}, int @var{$arg2}) +This probe is triggered when the @code{glibc.malloc.tcache_max} +tunable is set. Argument @var{$arg1} is the requested value, and +@var{$arg2} is the previous value of this tunable. +@end deftp + +@deftp Probe memory_tunable_tcache_count (int @var{$arg1}, int @var{$arg2}) +This probe is triggered when the @code{glibc.malloc.tcache_count} +tunable is set. Argument @var{$arg1} is the requested value, and +@var{$arg2} is the previous value of this tunable. +@end deftp + +@deftp Probe memory_tunable_tcache_unsorted_limit (int @var{$arg1}, int @var{$arg2}) +This probe is triggered when the +@code{glibc.malloc.tcache_unsorted_limit} tunable is set. Argument +@var{$arg1} is the requested value, and @var{$arg2} is the previous +value of this tunable. +@end deftp + @node Mathematical Function Probes @section Mathematical Function Probes diff -x .git -x po -rup glibc.pristine/manual/tunables.texi glibc.djmalloc-tcache/manual/tunables.texi --- glibc.pristine/manual/tunables.texi 2017-06-23 20:49:10.201148494 -0400 +++ glibc.djmalloc-tcache/manual/tunables.texi 2017-06-26 17:35:07.952998383 -0400 @@ -193,6 +193,39 @@ systems the limit is twice the number of is 8 times the number of cores online. @end deftp +@deftp Tunable glibc.malloc.tcache_max +The maximum size of a request (in bytes) which may be met via the +per-thread cache. The default (and maximum) value is 1032 bytes on +64-bit systems and 516 bytes on 32-bit systems. +@end deftp + +@deftp Tunable glibc.malloc.tcache_count +The maximum number of chunks of each size to cache. The default is 7. +There is no upper limit, other than available system memory. Note +that chunks are rounded up to malloc's guaranteed alignment - this +count is per rounded size, not per user-provided size. + +The approximate maximum overhead of the per-thread cache (for each +thread, of course) is thus @code{glibc.malloc.tcache_max} (in bins, +max 64 bins) times @code{glibc.malloc.tcache_count} times the size for +each bin. With defaults, this is about 236 KB on 64-bit systems and +118 KB on 32-bit systems. +@end deftp + +@deftp Tunable glibc.malloc.tcache_unsorted_limit +When the user requests memory and the request cannot be met via the +per-thread cache, the arenas are used to meet the request. At this +time, additional chunks will be moved from existing arena lists to +pre-fill the corresponding cache. While copies from the fastbins, +smallbins, and regular bins are bounded and predictable due to the bin +sizes, copies from the unsorted bin are not bounded, and incur +additional time penalties as they need to be sorted as they're +scanned. To make scanning the unsorted list more predictable and +bounded, the user may set this tunable to limit the number of blocks +that are scanned from the unsorted list while searching for chunks to +pre-fill the per-thread cache with. The default, or when set to zero, +is no limit. + @node Hardware Capability Tunables @section Hardware Capability Tunables @cindex hardware capability tunables