From: Peter Zijlstra <peterz@infradead.org> To: Michal Hocko <mhocko@kernel.org> Cc: Tim Chen <tim.c.chen@linux.intel.com>, Aaron Lu <aaron.lu@intel.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dave Hansen <dave.hansen@intel.com>, Tim Chen <tim.c.chen@intel.com>, Andrew Morton <akpm@linux-foundation.org>, Ying Huang <ying.huang@intel.com> Subject: Re: [PATCH v2 0/5] mm: support parallel free of memory Date: Fri, 17 Mar 2017 13:53:33 +0100 [thread overview] Message-ID: <20170317125333.xyhm5fl2srygxcbv@hirez.programming.kicks-ass.net> (raw) In-Reply-To: <20170317074707.GB26298@dhcp22.suse.cz> On Fri, Mar 17, 2017 at 08:47:08AM +0100, Michal Hocko wrote: > On Thu 16-03-17 11:36:21, Tim Chen wrote: > [...] > > Perhaps we can only do this expedited exit only when there are idle cpus around. > > We can use the root sched domain's overload indicator for such a quick check. > > This is not so easy, I am afraid. Those CPUs might be idle for a good > reason (power saving etc.). You will never know by simply checking > one metric. This is why doing these optimistic parallelization > optimizations is far from trivial. This is not the first time somebody > wants to do this. People are trying to make THP migration faster > doing the similar thing. I guess we really need a help from the > scheduler to do this properly, though. I've been thinking about an API > (e.g. try_to_run_in_backgroun) which would evaluate all these nasty > details and either return with -EBUSY or kick the background thread to > accomplish the work if the system is reasonably idle. I am not really > sure whether such an API is viable though. > Peter, what do you think? Much pain lies this way. Also, -enocontext.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org> To: Michal Hocko <mhocko@kernel.org> Cc: Tim Chen <tim.c.chen@linux.intel.com>, Aaron Lu <aaron.lu@intel.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dave Hansen <dave.hansen@intel.com>, Tim Chen <tim.c.chen@intel.com>, Andrew Morton <akpm@linux-foundation.org>, Ying Huang <ying.huang@intel.com> Subject: Re: [PATCH v2 0/5] mm: support parallel free of memory Date: Fri, 17 Mar 2017 13:53:33 +0100 [thread overview] Message-ID: <20170317125333.xyhm5fl2srygxcbv@hirez.programming.kicks-ass.net> (raw) In-Reply-To: <20170317074707.GB26298@dhcp22.suse.cz> On Fri, Mar 17, 2017 at 08:47:08AM +0100, Michal Hocko wrote: > On Thu 16-03-17 11:36:21, Tim Chen wrote: > [...] > > Perhaps we can only do this expedited exit only when there are idle cpus around. > > We can use the root sched domain's overload indicator for such a quick check. > > This is not so easy, I am afraid. Those CPUs might be idle for a good > reason (power saving etc.). You will never know by simply checking > one metric. This is why doing these optimistic parallelization > optimizations is far from trivial. This is not the first time somebody > wants to do this. People are trying to make THP migration faster > doing the similar thing. I guess we really need a help from the > scheduler to do this properly, though. I've been thinking about an API > (e.g. try_to_run_in_backgroun) which would evaluate all these nasty > details and either return with -EBUSY or kick the background thread to > accomplish the work if the system is reasonably idle. I am not really > sure whether such an API is viable though. > Peter, what do you think? Much pain lies this way. Also, -enocontext. -- 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:[~2017-03-17 12:53 UTC|newest] Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-15 8:59 [PATCH v2 0/5] mm: support parallel free of memory Aaron Lu 2017-03-15 8:59 ` Aaron Lu 2017-03-15 9:00 ` [PATCH v2 1/5] mm: add tlb_flush_mmu_free_batches Aaron Lu 2017-03-15 9:00 ` Aaron Lu 2017-03-15 9:00 ` [PATCH v2 2/5] mm: parallel free pages Aaron Lu 2017-03-15 9:00 ` Aaron Lu 2017-03-15 9:42 ` Hillf Danton 2017-03-15 9:42 ` Hillf Danton 2017-03-15 11:54 ` Aaron Lu 2017-03-15 11:54 ` Aaron Lu 2017-03-15 9:00 ` [PATCH v2 3/5] mm: use a dedicated workqueue for the free workers Aaron Lu 2017-03-15 9:00 ` Aaron Lu 2017-03-22 6:33 ` Minchan Kim 2017-03-22 6:33 ` Minchan Kim 2017-03-22 8:41 ` Aaron Lu 2017-03-22 8:41 ` Aaron Lu 2017-03-22 8:55 ` Minchan Kim 2017-03-22 8:55 ` Minchan Kim 2017-03-22 13:43 ` Aaron Lu 2017-03-22 13:43 ` Aaron Lu 2017-03-23 5:53 ` Minchan Kim 2017-03-23 5:53 ` Minchan Kim 2017-03-23 15:38 ` Dave Hansen 2017-03-23 15:38 ` Dave Hansen 2017-03-24 12:37 ` Aaron Lu 2017-03-24 12:37 ` Aaron Lu 2017-03-15 9:00 ` [PATCH v2 4/5] mm: add force_free_pages in zap_pte_range Aaron Lu 2017-03-15 9:00 ` Aaron Lu 2017-03-15 9:00 ` [PATCH v2 5/5] mm: add debugfs interface for parallel free tuning Aaron Lu 2017-03-15 9:00 ` Aaron Lu 2017-03-15 14:18 ` [PATCH v2 0/5] mm: support parallel free of memory Michal Hocko 2017-03-15 14:18 ` Michal Hocko 2017-03-15 15:44 ` Aaron Lu 2017-03-15 15:44 ` Aaron Lu 2017-03-15 16:28 ` Michal Hocko 2017-03-15 16:28 ` Michal Hocko 2017-03-15 21:38 ` Tim Chen 2017-03-15 21:38 ` Tim Chen 2017-03-16 9:07 ` Michal Hocko 2017-03-16 9:07 ` Michal Hocko 2017-03-16 18:36 ` Tim Chen 2017-03-16 18:36 ` Tim Chen 2017-03-17 7:47 ` Michal Hocko 2017-03-17 7:47 ` Michal Hocko 2017-03-17 8:07 ` Minchan Kim 2017-03-17 8:07 ` Minchan Kim 2017-03-17 12:33 ` Aaron Lu 2017-03-17 12:33 ` Aaron Lu 2017-03-17 12:59 ` Michal Hocko 2017-03-17 12:59 ` Michal Hocko 2017-03-17 13:16 ` Peter Zijlstra 2017-03-17 13:16 ` Peter Zijlstra 2017-03-17 12:53 ` Peter Zijlstra [this message] 2017-03-17 12:53 ` Peter Zijlstra 2017-03-17 13:05 ` Michal Hocko 2017-03-17 13:05 ` Michal Hocko 2017-03-21 14:54 ` Dave Hansen 2017-03-21 14:54 ` Dave Hansen 2017-03-22 8:02 ` Aaron Lu 2017-03-22 8:02 ` Aaron Lu 2017-03-24 7:04 ` Aaron Lu 2017-03-24 7:04 ` Aaron Lu 2017-03-21 15:18 ` Tim Chen 2017-03-21 15:18 ` Tim Chen 2017-03-16 6:54 ` Aaron Lu 2017-03-16 6:54 ` Aaron Lu 2017-03-16 7:34 ` Aaron Lu 2017-03-16 7:34 ` Aaron Lu 2017-03-16 13:51 ` Aaron Lu 2017-03-16 13:51 ` Aaron Lu 2017-03-16 14:14 ` Aaron Lu 2017-03-16 14:14 ` Aaron Lu 2017-03-15 14:56 ` Vlastimil Babka 2017-03-15 14:56 ` Vlastimil Babka 2017-03-15 15:50 ` Aaron Lu 2017-03-15 15:50 ` Aaron Lu 2017-03-17 3:10 ` Aaron Lu 2017-03-17 3:10 ` Aaron Lu 2017-03-16 19:38 ` Alex Thorlton 2017-03-16 19:38 ` Alex Thorlton 2017-03-17 2:21 ` Aaron Lu 2017-03-17 2:21 ` Aaron Lu 2017-03-20 19:15 ` Alex Thorlton 2017-03-20 19:15 ` Alex Thorlton
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