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Date: Mon, 13 Jun 2016 09:51:20 +0800 From: Ganesh Mahendran <opensource.ganesh@...il.com> To: Sergey Senozhatsky <sergey.senozhatsky@...il.com> Cc: Minchan Kim <minchan@...nel.org>, Linux-MM <linux-mm@...ck.org>, linux-kernel <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, Nitin Gupta <ngupta@...are.org>, Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>, rostedt@...dmis.org, mingo@...hat.com Subject: Re: [PATCH] mm/zsmalloc: add trace events for zs_compact Hi, Sergey: 2016-06-08 22:10 GMT+08:00 Sergey Senozhatsky <sergey.senozhatsky@...il.com>: > Hello, > > On (06/08/16 14:39), Ganesh Mahendran wrote: >> >> > On Tue, Jun 07, 2016 at 04:56:44PM +0800, Ganesh Mahendran wrote: >> >> >> Currently zsmalloc is widely used in android device. >> >> >> Sometimes, we want to see how frequently zs_compact is >> >> >> triggered or how may pages freed by zs_compact(), or which >> >> >> zsmalloc pool is compacted. >> >> >> >> >> >> Most of the time, user can get the brief information from >> >> >> trace_mm_shrink_slab_[start | end], but in some senario, >> >> >> they do not use zsmalloc shrinker, but trigger compaction manually. >> >> >> So add some trace events in zs_compact is convenient. Also we >> >> >> can add some zsmalloc specific information(pool name, total compact >> >> >> pages, etc) in zsmalloc trace. >> >> > >> >> > Sorry, I cannot understand what's the problem now and what you want to >> >> > solve. Could you elaborate it a bit? >> >> > >> >> > Thanks. >> >> >> >> We have backported the zs_compact() to our product(kernel 3.18). >> >> It is usefull for a longtime running device. >> >> But there is not a convenient way to get the detailed information >> >> of zs_comapct() which is usefull for performance optimization. >> >> Information about how much time zs_compact used, which pool is >> >> compacted, how many page freed, etc. > > sorry, couldn't check my email earlier. Sorry for the late response. I'm off for a few days annual leave. > > zs_compact() is just one of the N sites that are getting called by > the shrinker; optimization here will "solve" only 1/N of the problems. > are there any trace events in any other shrinker callbacks? Yes, there are trace events in ext4 shrinker: ----- fs/ext4/extents_status.c: ext4_es_scan() { trace_ext4_es_shrink_scan_enter(sbi->s_sb, nr_to_scan, ret); ... nr_shrunk = __es_shrink(sbi, nr_to_scan, NULL); trace_ext4_es_shrink_scan_exit(sbi->s_sb, nr_shrunk, ret); } ----- > > > why trace_mm_shrink_slab_start()/trace_mm_shrink_slab_end()/etc. don't work you? I think trace_mm_shrink_slab_start/end is for general usage. If we have some specific information(such as pool name, shrink count or others in the future), it will be convenient when we have zs_compact trace event. Also, if user do manually zs_compact instead of shrinker, he can get zs_compact information from trace event. Thanks. > > -ss
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