From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Weiner Subject: Re: [PATCH] mm: memcontrol: use per-cpu stocks for socket memory uncharging Date: Tue, 29 Aug 2017 15:26:21 -0400 Message-ID: <20170829192621.GA5447@cmpxchg.org> References: <20170829100150.4580-1-guro@fb.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=cmpxchg.org ; s=x; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject: Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=sU5l1qYG950Xbeuo6uGmiG4wPcwER8Fxdlffshp8a4U=; b=CuoRNWssYr7ySEJF8FYaZrctEJ GQtxRciQUTj0m7GEB0UEYKjQGhl70lfA6uIIMZClyGJ72e483blYucaLPolRFWlb9Ie7cuGs67fn1 UZ8RKn4SKfyFXxG8IM+rY5jskfxDX0+rQX8IcEUzjDF9mKjDE5DrZaYXoQLP6tRb/i14=; Content-Disposition: inline In-Reply-To: <20170829100150.4580-1-guro@fb.com> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Roman Gushchin Cc: linux-mm@kvack.org, Michal Hocko , Vladimir Davydov , cgroups@vger.kernel.org, kernel-team@fb.com, linux-kernel@vger.kernel.org On Tue, Aug 29, 2017 at 11:01:50AM +0100, Roman Gushchin wrote: > We've noticed a quite sensible performance overhead on some hosts > with significant network traffic when socket memory accounting > is enabled. > > Perf top shows that socket memory uncharging path is hot: > 2.13% [kernel] [k] page_counter_cancel > 1.14% [kernel] [k] __sk_mem_reduce_allocated > 1.14% [kernel] [k] _raw_spin_lock > 0.87% [kernel] [k] _raw_spin_lock_irqsave > 0.84% [kernel] [k] tcp_ack > 0.84% [kernel] [k] ixgbe_poll > 0.83% < workload > > 0.82% [kernel] [k] enqueue_entity > 0.68% [kernel] [k] __fget > 0.68% [kernel] [k] tcp_delack_timer_handler > 0.67% [kernel] [k] __schedule > 0.60% < workload > > 0.59% [kernel] [k] __inet6_lookup_established > 0.55% [kernel] [k] __switch_to > 0.55% [kernel] [k] menu_select > 0.54% libc-2.20.so [.] __memcpy_avx_unaligned > > To address this issue, the existing per-cpu stock infrastructure > can be used. > > refill_stock() can be called from mem_cgroup_uncharge_skmem() > to move charge to a per-cpu stock instead of calling atomic > page_counter_uncharge(). > > To prevent the uncontrolled growth of per-cpu stocks, > refill_stock() will explicitly drain the cached charge, > if the cached value exceeds CHARGE_BATCH. > > This allows significantly optimize the load: > 1.21% [kernel] [k] _raw_spin_lock > 1.01% [kernel] [k] ixgbe_poll > 0.92% [kernel] [k] _raw_spin_lock_irqsave > 0.90% [kernel] [k] enqueue_entity > 0.86% [kernel] [k] tcp_ack > 0.85% < workload > > 0.74% perf-11120.map [.] 0x000000000061bf24 > 0.73% [kernel] [k] __schedule > 0.67% [kernel] [k] __fget > 0.63% [kernel] [k] __inet6_lookup_established > 0.62% [kernel] [k] menu_select > 0.59% < workload > > 0.59% [kernel] [k] __switch_to > 0.57% libc-2.20.so [.] __memcpy_avx_unaligned > > Signed-off-by: Roman Gushchin > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Vladimir Davydov > Cc: cgroups@vger.kernel.org > Cc: kernel-team@fb.com > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org Acked-by: Johannes Weiner Neat! As far as other types of pages go: page cache and anon are already batched pretty well, but I think kmem might benefit from this too. Have you considered using the stock in memcg_kmem_uncharge()? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org