From: Mikulas Patocka <mpatocka@redhat.com> To: Michal Hocko <mhocko@kernel.org> Cc: NeilBrown <neilb@suse.com>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, LKML <linux-kernel@vger.kernel.org>, linux-mm@kvack.org, dm-devel@redhat.com, Mel Gorman <mgorman@suse.de>, David Rientjes <rientjes@google.com>, Ondrej Kozina <okozina@redhat.com>, Andrew Morton <akpm@linux-foundation.org> Subject: Re: [dm-devel] [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE tasks Date: Thu, 4 Aug 2016 14:46:07 -0400 (EDT) [thread overview] Message-ID: <alpine.LRH.2.02.1608041439420.21662@file01.intranet.prod.int.rdu2.redhat.com> (raw) In-Reply-To: <20160803144229.GD1490@dhcp22.suse.cz> On Wed, 3 Aug 2016, Michal Hocko wrote: > > > Even mempool allocations shouldn't allow reclaim to > > > scan pages too quickly even when LRU lists are full of dirty pages. But > > > as I've said that would restrict the success rates even under light page > > > cache load. Throttling on the wait_iff_congested should be quite rare. > > > > > > Anyway do you see an excessive throttling with the patch posted > > > http://lkml.kernel.org/r/20160725192344.GD2166@dhcp22.suse.cz ? Or from > > > > It didn't have much effect. > > > > Since the patch 4e390b2b2f34b8daaabf2df1df0cf8f798b87ddb (revert of the > > limitless mempool allocations), swapping to dm-crypt works in the simple > > example. > > OK. Do you see any throttling due to wait_iff_congested? No, but I've seen occasional stalls of mempool allocations in throttle_vm_writeout - but the patch that removed throttle_vm_writeout didn't improve overall speed, so the stalls were only minor. > writeback_wait_iff_congested trace point should help here. If not maybe > we should start with the above patch and see how it works in practise. > If the there is still an excessive and unexpected throttling then we > should move on to a more mempool/block layer users specific solution. Currently, dm-crypt reports the device congested only if the underlying block device is congested. But as others suggested, dm-crypt should report congested status if is clogged due to slow encryption progress - and in that case you should not throttle mempool allocations (because such throttling would decrease encryption speed even more). Mikulas > -- > Michal Hocko > SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Mikulas Patocka <mpatocka@redhat.com> To: Michal Hocko <mhocko@kernel.org> Cc: NeilBrown <neilb@suse.com>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, LKML <linux-kernel@vger.kernel.org>, linux-mm@kvack.org, dm-devel@redhat.com, Mel Gorman <mgorman@suse.de>, David Rientjes <rientjes@google.com>, Ondrej Kozina <okozina@redhat.com>, Andrew Morton <akpm@linux-foundation.org> Subject: Re: [dm-devel] [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE tasks Date: Thu, 4 Aug 2016 14:46:07 -0400 (EDT) [thread overview] Message-ID: <alpine.LRH.2.02.1608041439420.21662@file01.intranet.prod.int.rdu2.redhat.com> (raw) In-Reply-To: <20160803144229.GD1490@dhcp22.suse.cz> On Wed, 3 Aug 2016, Michal Hocko wrote: > > > Even mempool allocations shouldn't allow reclaim to > > > scan pages too quickly even when LRU lists are full of dirty pages. But > > > as I've said that would restrict the success rates even under light page > > > cache load. Throttling on the wait_iff_congested should be quite rare. > > > > > > Anyway do you see an excessive throttling with the patch posted > > > http://lkml.kernel.org/r/20160725192344.GD2166@dhcp22.suse.cz ? Or from > > > > It didn't have much effect. > > > > Since the patch 4e390b2b2f34b8daaabf2df1df0cf8f798b87ddb (revert of the > > limitless mempool allocations), swapping to dm-crypt works in the simple > > example. > > OK. Do you see any throttling due to wait_iff_congested? No, but I've seen occasional stalls of mempool allocations in throttle_vm_writeout - but the patch that removed throttle_vm_writeout didn't improve overall speed, so the stalls were only minor. > writeback_wait_iff_congested trace point should help here. If not maybe > we should start with the above patch and see how it works in practise. > If the there is still an excessive and unexpected throttling then we > should move on to a more mempool/block layer users specific solution. Currently, dm-crypt reports the device congested only if the underlying block device is congested. But as others suggested, dm-crypt should report congested status if is clogged due to slow encryption progress - and in that case you should not throttle mempool allocations (because such throttling would decrease encryption speed even more). Mikulas > -- > 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:[~2016-08-04 18:47 UTC|newest] Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-07-18 8:39 [RFC PATCH 0/2] mempool vs. page allocator interaction Michal Hocko 2016-07-18 8:39 ` Michal Hocko 2016-07-18 8:41 ` [RFC PATCH 1/2] mempool: do not consume memory reserves from the reclaim path Michal Hocko 2016-07-18 8:41 ` Michal Hocko 2016-07-18 8:41 ` [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE tasks Michal Hocko 2016-07-18 8:41 ` Michal Hocko 2016-07-19 21:50 ` Mikulas Patocka 2016-07-19 21:50 ` Mikulas Patocka 2016-07-22 8:46 ` NeilBrown 2016-07-22 9:04 ` NeilBrown 2016-07-22 9:15 ` Michal Hocko 2016-07-22 9:15 ` Michal Hocko 2016-07-23 0:12 ` NeilBrown 2016-07-25 8:32 ` Michal Hocko 2016-07-25 8:32 ` Michal Hocko 2016-07-25 19:23 ` Michal Hocko 2016-07-25 19:23 ` Michal Hocko 2016-07-25 19:23 ` Michal Hocko 2016-07-26 7:07 ` Michal Hocko 2016-07-26 7:07 ` Michal Hocko 2016-07-27 3:43 ` [dm-devel] " NeilBrown 2016-07-27 18:24 ` Michal Hocko 2016-07-27 18:24 ` Michal Hocko 2016-07-27 21:33 ` NeilBrown 2016-07-28 7:17 ` Michal Hocko 2016-07-28 7:17 ` Michal Hocko 2016-08-03 12:53 ` Mikulas Patocka 2016-08-03 12:53 ` Mikulas Patocka 2016-08-03 14:34 ` Michal Hocko 2016-08-03 14:34 ` Michal Hocko 2016-08-04 18:49 ` Mikulas Patocka 2016-08-04 18:49 ` Mikulas Patocka 2016-08-12 12:32 ` Michal Hocko 2016-08-12 12:32 ` Michal Hocko 2016-08-13 17:34 ` Mikulas Patocka 2016-08-13 17:34 ` Mikulas Patocka 2016-08-14 10:34 ` Michal Hocko 2016-08-14 10:34 ` Michal Hocko 2016-08-15 16:15 ` Mikulas Patocka 2016-08-15 16:15 ` Mikulas Patocka 2016-11-23 21:11 ` Mikulas Patocka 2016-11-23 21:11 ` Mikulas Patocka 2016-11-24 13:29 ` Michal Hocko 2016-11-24 13:29 ` Michal Hocko 2016-11-24 17:10 ` Mikulas Patocka 2016-11-24 17:10 ` Mikulas Patocka 2016-11-28 14:06 ` Michal Hocko 2016-11-28 14:06 ` Michal Hocko 2016-07-25 21:52 ` Mikulas Patocka 2016-07-25 21:52 ` Mikulas Patocka 2016-07-26 7:25 ` Michal Hocko 2016-07-26 7:25 ` Michal Hocko 2016-07-27 4:02 ` [dm-devel] " NeilBrown 2016-07-27 14:28 ` Mikulas Patocka 2016-07-27 14:28 ` Mikulas Patocka 2016-07-27 18:40 ` Michal Hocko 2016-07-27 18:40 ` Michal Hocko 2016-08-03 13:59 ` Mikulas Patocka 2016-08-03 13:59 ` Mikulas Patocka 2016-08-03 14:42 ` Michal Hocko 2016-08-03 14:42 ` Michal Hocko 2016-08-04 18:46 ` Mikulas Patocka [this message] 2016-08-04 18:46 ` Mikulas Patocka 2016-07-27 21:36 ` NeilBrown 2016-07-19 2:00 ` [RFC PATCH 1/2] mempool: do not consume memory reserves from the reclaim path David Rientjes 2016-07-19 2:00 ` David Rientjes 2016-07-19 7:49 ` Michal Hocko 2016-07-19 7:49 ` Michal Hocko 2016-07-19 13:54 ` Johannes Weiner 2016-07-19 13:54 ` Johannes Weiner 2016-07-19 14:19 ` Michal Hocko 2016-07-19 14:19 ` Michal Hocko 2016-07-19 22:01 ` Mikulas Patocka 2016-07-19 22:01 ` Mikulas Patocka 2016-07-19 20:45 ` David Rientjes 2016-07-19 20:45 ` David Rientjes 2016-07-20 8:15 ` Michal Hocko 2016-07-20 8:15 ` Michal Hocko 2016-07-20 21:06 ` David Rientjes 2016-07-20 21:06 ` David Rientjes 2016-07-21 8:52 ` Michal Hocko 2016-07-21 8:52 ` Michal Hocko 2016-07-21 12:13 ` Johannes Weiner 2016-07-21 12:13 ` Johannes Weiner 2016-07-21 14:53 ` Michal Hocko 2016-07-21 14:53 ` Michal Hocko 2016-07-21 14:53 ` Michal Hocko 2016-07-21 15:26 ` Johannes Weiner 2016-07-21 15:26 ` Johannes Weiner 2016-07-22 1:41 ` NeilBrown 2016-07-22 6:37 ` Michal Hocko 2016-07-22 6:37 ` Michal Hocko 2016-07-22 12:26 ` Vlastimil Babka 2016-07-22 12:26 ` Vlastimil Babka 2016-07-22 19:44 ` Andrew Morton 2016-07-22 19:44 ` Andrew Morton 2016-07-23 18:52 ` Vlastimil Babka 2016-07-23 18:52 ` Vlastimil Babka 2016-07-19 21:50 ` Mikulas Patocka 2016-07-19 21:50 ` Mikulas Patocka 2016-07-20 6:44 ` Michal Hocko 2016-07-20 6:44 ` Michal Hocko
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