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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=wT+MufMGEB0ufjSt00Zd8HTGo5TcuBRHX37P346pxcM=; b=ZnzujSEbax23GqstRnJMfugfRQIVcnioLid6dLybj07wx9hjP/41wInCr4eFCaA0ysgQ2u 2+m4YnrwfxksKjvo8a/WrfxC+BfgIIHHf8qZ00cON1a9Wr9jnRxDYseMou3Vy+3CjQhEoS J7kFa8LNWBSIXVkHPqSh0ulE+SrFXak= Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id E7ED51379A; Mon, 27 Nov 2023 09:33:49 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 7kaON31iZGX6QgAAD6G6ig (envelope-from ); Mon, 27 Nov 2023 09:33:49 +0000 Date: Mon, 27 Nov 2023 10:33:49 +0100 From: Michal Hocko To: Dmitry Rokosov Cc: rostedt@goodmis.org, mhiramat@kernel.org, hannes@cmpxchg.org, roman.gushchin@linux.dev, shakeelb@google.com, muchun.song@linux.dev, akpm@linux-foundation.org, kernel@sberdevices.ru, rockosov@gmail.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH v3 2/2] mm: memcg: introduce new event to trace shrink_memcg Message-ID: References: <20231123193937.11628-1-ddrokosov@salutedevices.com> <20231123193937.11628-3-ddrokosov@salutedevices.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231123193937.11628-3-ddrokosov@salutedevices.com> X-Rspamd-Queue-Id: B6FC1C0015 X-Rspam-User: X-Stat-Signature: p49gzdu1te4ujfh37z4csupcxnbaiku9 X-Rspamd-Server: rspam03 X-HE-Tag: 1701077631-660157 X-HE-Meta: U2FsdGVkX18zeZn22Yw0oHwNE3uyqVq7lU9cQxDyd5XEULWAKBsa4kP8HzXNykgmNv6ogD9JEKCal3061wUVKt2f3BwljCzL40c5QxYAdUT1izgKgAkpC8vv7BFI5Wg+U9Ksq79XbRUsUwCT+KNORWe7Bj+NP5MDgizmA3i5pzeCeDQuca9XpkX+uiZCZlQoaPRPco1+9OSYBREP1aQldfv71jG00LvnsGn4knsEYfHRpgGzdFJqHicLodYtgFSnHHVvbC1YoNgCO+WkVDoo3ubSMNKNEDkBxiT2f1sNyV6qZHpQV1X+TjE3huxEbRwdN2uLT+H2WSq8vci0kOIQRGBovZxuCM1ANEDTiXGNLU0/3S3+EtttCtVVocx+jAQjsPjKyI8wMOfrrDNPHfCcW7quew8uGUt0vGp676SjtLKIuDqUrJ4Jf2vFhh206YrHfLcUMZdJa2BnVcsPg4gASvdpEDVPnGXGDvnOeku5HsCS5/2AHHRmcRis2EItGY3laC4L5eNAYCU4ijr9g552LppAyKlTkX0ENl07oZIQKoorkz3v6vjx4pslAczTTVhVzmWKFcoFG2ojpmkAAkr3cFc8Hl9YFXrXCg7SyaGBcI8+ZwCyyDfrHcWX38/HY7usZbmcd1WWJzab9GPrZk6IxWKoFwb5/DgqOFy5frjepfNWg0oL20on9FQDuIgo1QyVtoTp/Eq+SPorMw+4RGl7XyYnpiSIKEl2lXLkaHaG97sYvv40VmMMiYmLi8gLBjni2gtK92qss3DicU6796OhD5lP5LO8gkjx84tZZwAKIzm+GSBhwIP4s98wwyuVgcMd9mNAY1g4Il6/o1gBcOPni3UG0kAnPbBmAh6bd9Domu+tZ/q/eWRxNewWjWTvN40WtP900YX+QGfGgDAlRnF9RDye5iXxm/gULnzVlxcwSGS1cDPNFOiBAu1qQEWAOpdTJDnxVjVjZ2i3M6AThod QfrQZTzZ Pc8V61yAEhgZbJU482jrgAXm492FmGgDgG07Te8zv35gtjtEUC/hodur1QMrQrTIuVEk/JJOW4VBJUl+qhoLtOYzfwQhkgOAYBMAYyT9QuXlQptm0sP+QGc38mXvV+MrB8XRalRl9qV6n16g9gfTxZ27xW/+CeUUQOSZM71hj21vZM71T7iDY+YjteJd7xk55MKpaGeFAe14TjuJh5nwOjgL0lETIuBSwRnM8we9PHOh2rnqAVbzM0Tc7K1LFFQAXAT2N74rqN+//VSk= 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: List-Subscribe: List-Unsubscribe: On Thu 23-11-23 22:39:37, Dmitry Rokosov wrote: > The shrink_memcg flow plays a crucial role in memcg reclamation. > Currently, it is not possible to trace this point from non-direct > reclaim paths. However, direct reclaim has its own tracepoint, so there > is no issue there. In certain cases, when debugging memcg pressure, > developers may need to identify all potential requests for memcg > reclamation including kswapd(). The patchset introduces the tracepoints > mm_vmscan_memcg_shrink_{begin|end}() to address this problem. > > Example of output in the kswapd context (non-direct reclaim): > kswapd0-39 [001] ..... 240.356378: mm_vmscan_memcg_shrink_begin: order=0 gfp_flags=GFP_KERNEL memcg=16 > kswapd0-39 [001] ..... 240.356396: mm_vmscan_memcg_shrink_end: nr_reclaimed=0 memcg=16 > kswapd0-39 [001] ..... 240.356420: mm_vmscan_memcg_shrink_begin: order=0 gfp_flags=GFP_KERNEL memcg=16 > kswapd0-39 [001] ..... 240.356454: mm_vmscan_memcg_shrink_end: nr_reclaimed=1 memcg=16 > kswapd0-39 [001] ..... 240.356479: mm_vmscan_memcg_shrink_begin: order=0 gfp_flags=GFP_KERNEL memcg=16 > kswapd0-39 [001] ..... 240.356506: mm_vmscan_memcg_shrink_end: nr_reclaimed=4 memcg=16 > kswapd0-39 [001] ..... 240.356525: mm_vmscan_memcg_shrink_begin: order=0 gfp_flags=GFP_KERNEL memcg=16 > kswapd0-39 [001] ..... 240.356593: mm_vmscan_memcg_shrink_end: nr_reclaimed=11 memcg=16 > kswapd0-39 [001] ..... 240.356614: mm_vmscan_memcg_shrink_begin: order=0 gfp_flags=GFP_KERNEL memcg=16 > kswapd0-39 [001] ..... 240.356738: mm_vmscan_memcg_shrink_end: nr_reclaimed=25 memcg=16 > kswapd0-39 [001] ..... 240.356790: mm_vmscan_memcg_shrink_begin: order=0 gfp_flags=GFP_KERNEL memcg=16 > kswapd0-39 [001] ..... 240.357125: mm_vmscan_memcg_shrink_end: nr_reclaimed=53 memcg=16 In the previous version I have asked why do we need this specific tracepoint when we already do have trace_mm_vmscan_lru_shrink_{in}active which already give you a very good insight. That includes the number of reclaimed pages but also more. I do see that we do not include memcg id of the reclaimed LRU, but that shouldn't be a big problem to add, no? -- Michal Hocko SUSE Labs