From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7BD2E14F63 for ; Fri, 12 Jan 2024 19:25:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="j1gqicPf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C58E6C43390; Fri, 12 Jan 2024 19:25:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1705087551; bh=zj+wrk3JU3+5ZfvCnM81nr4JfGpcqQFEcx5vMnuF40Y=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=j1gqicPfwW+sqefG8tW1Y9VcYwQbES5rX7TWVmY5AlkUyNYYYqX90KBWlliAONQJs VqHG2D46bPlY9nGlAx6JP1QINnzPrJeiI5vUUMwh84Udom1UxjTxG8jPMZA3T2A+2k UonS7vOhpRtg7zrwf9X/LQ5GKX/dIG/KO6OCJ+Co= Date: Fri, 12 Jan 2024 11:25:51 -0800 From: Andrew Morton To: "Bang Li" Cc: , , =?UTF-8?Q?"?= =?UTF-8?Q?=E6=9C=B1=E8=BE=89(=E8=8C=B6=E6=B0=B4)"?= , "Yan Yan(cailing)" Subject: Re: [PATCH] mm/compaction: Reduce unnecessary loops Message-Id: <20240112112551.bbc9d5114fd2c6fb421fed2d@linux-foundation.org> In-Reply-To: <20240112073524.80724-1-libang.li@antgroup.com> References: <20240112073524.80724-1-libang.li@antgroup.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 12 Jan 2024 15:35:24 +0800 "Bang Li" wrote: > Compaction will be triggered when we write 1 to '/proc/sys/vm/ > compact_memory'. During the execution of the process, when we send > SIGKILL to terminate the compaction, the process does not exit > immediately. Instead, it will continue to loop through the remaining > zones and nodes before exiting. > > in my environment: > > [root]# cat /proc/buddyinfo > Node 0, zone DMA 1 1 1 0 2 1 1 0 1 1 3 > Node 0, zone DMA32 1666 1123 804 625 488 356 321 278 209 178 250 > Node 0, zone Normal 58852 83160 49983 9812 2287 1229 19604 24471 10346 5219 12205 > [root]# echo 1 > /sys/kernel/debug/tracing/events/compaction/mm_compaction_end/enable > > before the patch: > > [root]# timeout --signal=SIGKILL 0.002 bash -c 'echo 1 > /proc/sys/vm/compact_memory' > [root]# cat /sys/kernel/debug/tracing/trace_pipe > <...>-26494 [014] ..... 226.468993: mm_compaction_end: zone_start=0x1 migrate_pfn=0xe00 free_pfn=0xe00 zone_end=0x1000, mode=sync status=complete > <...>-26494 [014] ..... 226.469718: mm_compaction_end: zone_start=0x1000 migrate_pfn=0x20a80 free_pfn=0xffe00 zone_end=0x100000, mode=sync status=contended > <...>-26494 [014] ..... 226.469720: mm_compaction_end: zone_start=0x100000 migrate_pfn=0x100000 free_pfn=0x307fe00 zone_end=0x3080000, mode=sync status=contended > > after the patch: > > [root]# timeout --signal=SIGKILL 0.002 bash -c 'echo 1 > /proc/sys/vm/compact_memory' > [root]# cat /sys/kernel/debug/tracing/trace_pipe > <...>-17491 [053] ..... 109.005387: mm_compaction_end: zone_start=0x1 migrate_pfn=0xe00 free_pfn=0xe00 zone_end=0x1000, mode=sync status=complete > <...>-17491 [053] ..... 109.006139: mm_compaction_end: zone_start=0x1000 migrate_pfn=0x22220 free_pfn=0xffe00 zone_end=0x100000, mode=sync status=contended > > Although it exits quickly after receiving the SIGKILL signal, a better > solution is to terminate the loop early after receiving the SIGKILL > signal. > What is the use case here? The requirement? Why is this change valuable to anyone?