From: Michal Hocko <mhocko@kernel.org> To: Mel Gorman <mgorman@suse.de> Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>, Johannes Weiner <hannes@cmpxchg.org>, Vlastimil Babka <vbabka@suse.cz>, Rik van Riel <riel@redhat.com>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Date: Fri, 30 Dec 2016 10:36:55 +0100 [thread overview] Message-ID: <20161230093654.GC13301@dhcp22.suse.cz> (raw) In-Reply-To: <20161230091117.nkxn3bnhle3bofhw@suse.de> On Fri 30-12-16 09:11:17, Mel Gorman wrote: > On Wed, Dec 28, 2016 at 04:30:25PM +0100, Michal Hocko wrote: > > Hi, > > while debugging [1] I've realized that there is some room for > > improvements in the tracepoints set we offer currently. I had hard times > > to make any conclusion from the existing ones. The resulting problem > > turned out to be active list aging [2] and we are missing at least two > > tracepoints to debug such a problem. > > > > Some existing tracepoints could export more information to see _why_ the > > reclaim progress cannot be made not only _how much_ we could reclaim. > > The later could be seen quite reasonably from the vmstat counters > > already. It can be argued that we are showing too many implementation > > details in those tracepoints but I consider them way too lowlevel > > already to be usable by any kernel independent userspace. I would be > > _really_ surprised if anything but debugging tools have used them. > > > > Any feedback is highly appreciated. > > > > There is some minor overhead introduced in some paths regardless of > whether the tracepoints are active or not but I suspect it's negligible > in the context of the overhead of reclaim in general so; I will work on improving some of them. E.g. I've dropped the change to free_hot_cold_page_list because that is indeed a hot path but other than that there shouldn't be any even medium hot path which should see any overhead I can see. If you are aware of any, please let me know and I will think about how to improve it. > Acked-by: Mel Gorman <mgorman@suse.de> Thanks! -- Michal Hocko SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: Mel Gorman <mgorman@suse.de> Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>, Johannes Weiner <hannes@cmpxchg.org>, Vlastimil Babka <vbabka@suse.cz>, Rik van Riel <riel@redhat.com>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Date: Fri, 30 Dec 2016 10:36:55 +0100 [thread overview] Message-ID: <20161230093654.GC13301@dhcp22.suse.cz> (raw) In-Reply-To: <20161230091117.nkxn3bnhle3bofhw@suse.de> On Fri 30-12-16 09:11:17, Mel Gorman wrote: > On Wed, Dec 28, 2016 at 04:30:25PM +0100, Michal Hocko wrote: > > Hi, > > while debugging [1] I've realized that there is some room for > > improvements in the tracepoints set we offer currently. I had hard times > > to make any conclusion from the existing ones. The resulting problem > > turned out to be active list aging [2] and we are missing at least two > > tracepoints to debug such a problem. > > > > Some existing tracepoints could export more information to see _why_ the > > reclaim progress cannot be made not only _how much_ we could reclaim. > > The later could be seen quite reasonably from the vmstat counters > > already. It can be argued that we are showing too many implementation > > details in those tracepoints but I consider them way too lowlevel > > already to be usable by any kernel independent userspace. I would be > > _really_ surprised if anything but debugging tools have used them. > > > > Any feedback is highly appreciated. > > > > There is some minor overhead introduced in some paths regardless of > whether the tracepoints are active or not but I suspect it's negligible > in the context of the overhead of reclaim in general so; I will work on improving some of them. E.g. I've dropped the change to free_hot_cold_page_list because that is indeed a hot path but other than that there shouldn't be any even medium hot path which should see any overhead I can see. If you are aware of any, please let me know and I will think about how to improve it. > Acked-by: Mel Gorman <mgorman@suse.de> Thanks! -- Michal Hocko SUSE Labs -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-12-30 9:37 UTC|newest] Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-12-28 15:30 [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Michal Hocko 2016-12-28 15:30 ` Michal Hocko 2016-12-28 15:30 ` [PATCH 1/7] mm, vmscan: remove unused mm_vmscan_memcg_isolate Michal Hocko 2016-12-28 15:30 ` Michal Hocko 2016-12-29 7:33 ` Hillf Danton 2016-12-29 7:33 ` Hillf Danton 2016-12-28 15:30 ` [PATCH 2/7] mm, vmscan: add active list aging tracepoint Michal Hocko 2016-12-28 15:30 ` Michal Hocko 2016-12-29 5:33 ` Minchan Kim 2016-12-29 5:33 ` Minchan Kim 2016-12-29 7:52 ` Michal Hocko 2016-12-29 7:52 ` Michal Hocko 2016-12-30 1:48 ` Minchan Kim 2016-12-30 1:48 ` Minchan Kim 2016-12-30 9:26 ` Michal Hocko 2016-12-30 9:26 ` Michal Hocko 2016-12-30 9:38 ` Hillf Danton 2016-12-30 9:38 ` Hillf Danton 2016-12-30 16:04 ` Minchan Kim 2016-12-30 16:04 ` Minchan Kim 2016-12-30 16:37 ` Michal Hocko 2016-12-30 16:37 ` Michal Hocko 2016-12-30 17:30 ` Michal Hocko 2016-12-30 17:30 ` Michal Hocko 2017-01-03 5:03 ` Minchan Kim 2017-01-03 5:03 ` Minchan Kim 2017-01-03 8:21 ` Michal Hocko 2017-01-03 8:21 ` Michal Hocko 2017-01-04 5:07 ` Minchan Kim 2017-01-04 5:07 ` Minchan Kim 2017-01-04 7:28 ` Vlastimil Babka 2017-01-04 7:28 ` Vlastimil Babka 2017-01-04 7:50 ` Michal Hocko 2017-01-04 7:50 ` Michal Hocko 2016-12-29 7:44 ` Hillf Danton 2016-12-29 7:44 ` Hillf Danton 2016-12-28 15:30 ` [PATCH 3/7] mm, vmscan: show the number of skipped pages in mm_vmscan_lru_isolate Michal Hocko 2016-12-28 15:30 ` Michal Hocko 2016-12-29 5:53 ` Minchan Kim 2016-12-29 5:53 ` Minchan Kim 2016-12-29 7:49 ` Hillf Danton 2016-12-29 7:49 ` Hillf Danton 2017-01-03 17:21 ` Vlastimil Babka 2017-01-03 17:21 ` Vlastimil Babka 2017-01-03 20:43 ` Michal Hocko 2017-01-03 20:43 ` Michal Hocko 2016-12-28 15:30 ` [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepoint Michal Hocko 2016-12-28 15:30 ` Michal Hocko 2016-12-28 15:50 ` Nikolay Borisov 2016-12-28 15:50 ` Nikolay Borisov 2016-12-28 16:00 ` Michal Hocko 2016-12-28 16:00 ` Michal Hocko 2016-12-28 16:40 ` Nikolay Borisov 2016-12-28 16:40 ` Nikolay Borisov 2016-12-28 16:49 ` Michal Hocko 2016-12-28 16:49 ` Michal Hocko 2016-12-29 6:02 ` Minchan Kim 2016-12-29 6:02 ` Minchan Kim 2016-12-29 7:56 ` Michal Hocko 2016-12-29 7:56 ` Michal Hocko 2016-12-30 1:56 ` Minchan Kim 2016-12-30 1:56 ` Minchan Kim 2016-12-30 9:33 ` Michal Hocko 2016-12-30 9:33 ` Michal Hocko 2016-12-29 7:53 ` Hillf Danton 2016-12-29 7:53 ` Hillf Danton 2017-01-03 17:08 ` Vlastimil Babka 2017-01-03 17:08 ` Vlastimil Babka 2017-01-03 20:47 ` Michal Hocko 2017-01-03 20:47 ` Michal Hocko 2017-01-03 20:52 ` Michal Hocko 2017-01-03 20:52 ` Michal Hocko 2017-01-03 21:24 ` Michal Hocko 2017-01-03 21:24 ` Michal Hocko 2017-01-03 21:40 ` Vlastimil Babka 2017-01-03 21:40 ` Vlastimil Babka 2017-01-03 21:48 ` Michal Hocko 2017-01-03 21:48 ` Michal Hocko 2016-12-28 15:30 ` [PATCH 5/7] mm, vmscan: extract shrink_page_list reclaim counters into a struct Michal Hocko 2016-12-28 15:30 ` Michal Hocko 2016-12-29 8:00 ` Hillf Danton 2016-12-29 8:00 ` Hillf Danton 2016-12-28 15:30 ` [PATCH 6/7] mm, vmscan: enhance mm_vmscan_lru_shrink_inactive tracepoint Michal Hocko 2016-12-28 15:30 ` Michal Hocko 2016-12-29 8:05 ` Hillf Danton 2016-12-29 8:05 ` Hillf Danton 2016-12-28 15:30 ` [PATCH 7/7] mm, vmscan: add mm_vmscan_inactive_list_is_low tracepoint Michal Hocko 2016-12-28 15:30 ` Michal Hocko 2016-12-29 8:19 ` Hillf Danton 2016-12-29 8:19 ` Hillf Danton 2016-12-30 9:11 ` [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Mel Gorman 2016-12-30 9:11 ` Mel Gorman 2016-12-30 9:36 ` Michal Hocko [this message] 2016-12-30 9:36 ` Michal Hocko 2016-12-30 10:20 ` Mel Gorman 2016-12-30 10:20 ` Mel Gorman
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