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[46.135.85.121]) by smtp.gmail.com with ESMTPSA id w9-20020a056402070900b00525683f9b2fsm7945317edx.5.2023.08.22.11.41.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Aug 2023 11:41:58 -0700 (PDT) From: Mateusz Guzik To: linux-kernel@vger.kernel.org Cc: dennis@kernel.org, tj@kernel.org, cl@linux.com, akpm@linux-foundation.org, shakeelb@google.com, linux-mm@kvack.org, Mateusz Guzik Subject: [PATCH v2 1/2] pcpcntr: add group allocation/free Date: Tue, 22 Aug 2023 20:41:51 +0200 Message-Id: <20230822184152.2194558-2-mjguzik@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230822184152.2194558-1-mjguzik@gmail.com> References: <20230822184152.2194558-1-mjguzik@gmail.com> MIME-Version: 1.0 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 08DE316000D X-Stat-Signature: 1nhmozq1kyxigad7zrsduq8xumjsu5i3 X-Rspam-User: X-HE-Tag: 1692729720-928837 X-HE-Meta: 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 Reb84k2E 50V0Pf8UiozGC97uZdPLFAq3N003fzcwkm++VzsslzP9Al/jddlJlI4m4coaUJZVacR8ndsCDDhUpZLThtmHLmCVPIVe1V5ddvzFoEFjMzPVuENwnJ7Ty9fjcQXzFdwbhPfhwTJrKqp+NFkKEwJg4aOJXkyTWuaPtn4jdFAks78WYZSArXD3NEAdxF5rKySLEKxnJpyM6ouSAOPIm0NKhFrJLiWNKTTmClzAbG4cDcUQvhCYsWNfAQtfJlQXVXHtKVyewbh0Nt5lkXZzXm2/sgxYqFkdboPcyb2RCS8QZMR9sZRsKK9lImxSpJEVckxQM8QQp7DV/WuGDxb3aD8yiak7dRWFanpe7ylGX+I3J5IfsU1WgNc9ViSXRrNxnN743Dn4JCsBhnccRRqoW3bdd3K4lmkO+lVGdp6Jy1Nhkm3zrevKgfLlwAxsBfyuv9jSme/6d X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Allocations and frees are globally serialized on the pcpu lock (and the CPU hotplug lock if enabled, which is the case on Debian). At least one frequent consumer allocates 4 back-to-back counters (and frees them in the same manner), exacerbating the problem. While this does not fully remedy scalability issues, it is a step towards that goal and provides immediate relief. Signed-off-by: Mateusz Guzik --- include/linux/percpu_counter.h | 20 ++++++++--- lib/percpu_counter.c | 61 +++++++++++++++++++++++----------- 2 files changed, 57 insertions(+), 24 deletions(-) diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h index 75b73c83bc9d..518a4088b964 100644 --- a/include/linux/percpu_counter.h +++ b/include/linux/percpu_counter.h @@ -30,17 +30,27 @@ struct percpu_counter { extern int percpu_counter_batch; -int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp, - struct lock_class_key *key); +int __percpu_counter_init_many(struct percpu_counter *fbc, s64 amount, gfp_t gfp, + u32 nr_counters, struct lock_class_key *key); -#define percpu_counter_init(fbc, value, gfp) \ +#define percpu_counter_init_many(fbc, value, gfp, nr_counters) \ ({ \ static struct lock_class_key __key; \ \ - __percpu_counter_init(fbc, value, gfp, &__key); \ + __percpu_counter_init_many(fbc, value, gfp, nr_counters,\ + &__key); \ }) -void percpu_counter_destroy(struct percpu_counter *fbc); + +#define percpu_counter_init(fbc, value, gfp) \ + percpu_counter_init_many(fbc, value, gfp, 1) + +void percpu_counter_destroy_many(struct percpu_counter *fbc, u32 nr_counters); +static inline void percpu_counter_destroy(struct percpu_counter *fbc) +{ + percpu_counter_destroy_many(fbc, 1); +} + void percpu_counter_set(struct percpu_counter *fbc, s64 amount); void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch); diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c index 5004463c4f9f..9338b27f1cdd 100644 --- a/lib/percpu_counter.c +++ b/lib/percpu_counter.c @@ -151,48 +151,71 @@ s64 __percpu_counter_sum(struct percpu_counter *fbc) } EXPORT_SYMBOL(__percpu_counter_sum); -int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp, - struct lock_class_key *key) +int __percpu_counter_init_many(struct percpu_counter *fbc, s64 amount, gfp_t gfp, + u32 nr_counters, struct lock_class_key *key) { unsigned long flags __maybe_unused; - - raw_spin_lock_init(&fbc->lock); - lockdep_set_class(&fbc->lock, key); - fbc->count = amount; - fbc->counters = alloc_percpu_gfp(s32, gfp); - if (!fbc->counters) + size_t counter_size; + s32 __percpu *counters; + u32 i; + + counter_size = ALIGN(sizeof(*counters), __alignof__(*counters)); + counters = __alloc_percpu_gfp(nr_counters * counter_size, + __alignof__(*counters), gfp); + if (!counters) { + fbc[0].counters = NULL; return -ENOMEM; + } - debug_percpu_counter_activate(fbc); + for (i = 0; i < nr_counters; i++) { + raw_spin_lock_init(&fbc[i].lock); + lockdep_set_class(&fbc[i].lock, key); +#ifdef CONFIG_HOTPLUG_CPU + INIT_LIST_HEAD(&fbc[i].list); +#endif + fbc[i].count = amount; + fbc[i].counters = (void *)counters + (i * counter_size); + + debug_percpu_counter_activate(&fbc[i]); + } #ifdef CONFIG_HOTPLUG_CPU - INIT_LIST_HEAD(&fbc->list); spin_lock_irqsave(&percpu_counters_lock, flags); - list_add(&fbc->list, &percpu_counters); + for (i = 0; i < nr_counters; i++) + list_add(&fbc[i].list, &percpu_counters); spin_unlock_irqrestore(&percpu_counters_lock, flags); #endif return 0; } -EXPORT_SYMBOL(__percpu_counter_init); +EXPORT_SYMBOL(__percpu_counter_init_many); -void percpu_counter_destroy(struct percpu_counter *fbc) +void percpu_counter_destroy_many(struct percpu_counter *fbc, u32 nr_counters) { unsigned long flags __maybe_unused; + u32 i; + + if (WARN_ON_ONCE(!fbc)) + return; - if (!fbc->counters) + if (!fbc[0].counters) return; - debug_percpu_counter_deactivate(fbc); + for (i = 0; i < nr_counters; i++) + debug_percpu_counter_deactivate(&fbc[i]); #ifdef CONFIG_HOTPLUG_CPU spin_lock_irqsave(&percpu_counters_lock, flags); - list_del(&fbc->list); + for (i = 0; i < nr_counters; i++) + list_del(&fbc[i].list); spin_unlock_irqrestore(&percpu_counters_lock, flags); #endif - free_percpu(fbc->counters); - fbc->counters = NULL; + + free_percpu(fbc[0].counters); + + for (i = 0; i < nr_counters; i++) + fbc[i].counters = NULL; } -EXPORT_SYMBOL(percpu_counter_destroy); +EXPORT_SYMBOL(percpu_counter_destroy_many); int percpu_counter_batch __read_mostly = 32; 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[46.135.85.121]) by smtp.gmail.com with ESMTPSA id w9-20020a056402070900b00525683f9b2fsm7945317edx.5.2023.08.22.11.41.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Aug 2023 11:42:00 -0700 (PDT) From: Mateusz Guzik To: linux-kernel@vger.kernel.org Cc: dennis@kernel.org, tj@kernel.org, cl@linux.com, akpm@linux-foundation.org, shakeelb@google.com, linux-mm@kvack.org, Mateusz Guzik Subject: [PATCH v2 2/2] fork: group allocation of per-cpu counters for mm struct Date: Tue, 22 Aug 2023 20:41:52 +0200 Message-Id: <20230822184152.2194558-3-mjguzik@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230822184152.2194558-1-mjguzik@gmail.com> References: <20230822184152.2194558-1-mjguzik@gmail.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 2DD471C0008 X-Stat-Signature: pz98o4hq6jbt5ysifzxfwjoo5qeinn5w X-HE-Tag: 1692729721-241946 X-HE-Meta: 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 TiFPWPK8 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: A trivial execve scalability test which tries to be very friendly (statically linked binaries, all separate) is predominantly bottlenecked by back-to-back per-cpu counter allocations which serialize on global locks. Ease the pain by allocating and freeing them in one go. Bench can be found here: http://apollo.backplane.com/DFlyMisc/doexec.c $ cc -static -O2 -o static-doexec doexec.c $ ./static-doexec $(nproc) Even at a very modest scale of 26 cores (ops/s): before: 133543.63 after: 186061.81 (+39%) While with the patch these allocations remain a significant problem, the primary bottleneck shifts to: __pv_queued_spin_lock_slowpath+1 _raw_spin_lock_irqsave+57 folio_lruvec_lock_irqsave+91 release_pages+590 tlb_batch_pages_flush+61 tlb_finish_mmu+101 exit_mmap+327 __mmput+61 begin_new_exec+1245 load_elf_binary+712 bprm_execve+644 do_execveat_common.isra.0+429 __x64_sys_execve+50 do_syscall_64+46 entry_SYSCALL_64_after_hwframe+110 Signed-off-by: Mateusz Guzik --- kernel/fork.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index d2e12b6d2b18..4f0ada33457e 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -909,8 +909,6 @@ static void cleanup_lazy_tlbs(struct mm_struct *mm) */ void __mmdrop(struct mm_struct *mm) { - int i; - BUG_ON(mm == &init_mm); WARN_ON_ONCE(mm == current->mm); @@ -925,9 +923,8 @@ void __mmdrop(struct mm_struct *mm) put_user_ns(mm->user_ns); mm_pasid_drop(mm); mm_destroy_cid(mm); + percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS); - for (i = 0; i < NR_MM_COUNTERS; i++) - percpu_counter_destroy(&mm->rss_stat[i]); free_mm(mm); } EXPORT_SYMBOL_GPL(__mmdrop); @@ -1252,8 +1249,6 @@ static void mm_init_uprobes_state(struct mm_struct *mm) static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, struct user_namespace *user_ns) { - int i; - mt_init_flags(&mm->mm_mt, MM_MT_FLAGS); mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock); atomic_set(&mm->mm_users, 1); @@ -1301,17 +1296,14 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, if (mm_alloc_cid(mm)) goto fail_cid; - for (i = 0; i < NR_MM_COUNTERS; i++) - if (percpu_counter_init(&mm->rss_stat[i], 0, GFP_KERNEL_ACCOUNT)) - goto fail_pcpu; + if (percpu_counter_init_many(mm->rss_stat, 0, GFP_KERNEL_ACCOUNT, NR_MM_COUNTERS)) + goto fail_pcpu; mm->user_ns = get_user_ns(user_ns); lru_gen_init_mm(mm); return mm; fail_pcpu: - while (i > 0) - percpu_counter_destroy(&mm->rss_stat[--i]); mm_destroy_cid(mm); fail_cid: destroy_context(mm);