From: Matthew Wilcox <willy@infradead.org>
To: Aaron Lu <aaron.lu@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Huang Ying <ying.huang@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Kemi Wang <kemi.wang@intel.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Andi Kleen <ak@linux.intel.com>,
Mel Gorman <mgorman@techsingularity.net>,
David Rientjes <rientjes@google.com>
Subject: Re: [PATCH v4 3/3] mm/free_pcppages_bulk: prefetch buddy while not holding lock
Date: Tue, 6 Mar 2018 04:53:04 -0800 [thread overview]
Message-ID: <20180306125303.GA13722@bombadil.infradead.org> (raw)
In-Reply-To: <20180306122733.GA9664@intel.com>
On Tue, Mar 06, 2018 at 08:27:33PM +0800, Aaron Lu wrote:
> On Tue, Mar 06, 2018 at 08:55:57AM +0100, Vlastimil Babka wrote:
> > So the adjacent line prefetch might be disabled? Could you check bios or
> > the MSR mentioned in
> > https://software.intel.com/en-us/articles/disclosure-of-hw-prefetcher-control-on-some-intel-processors
>
> root@lkp-bdw-ep2 ~# rdmsr 0x1a4
> 0
Technically 0x1a4 is per-core, so you should run rdmsr -a 0x1a4 in order to
check all the cores. But I can't imagine they're being set differently on
each core.
> > instructions (calculated from itlb misses and insns-per-itlb-miss) shows
> > less than 1% increase, so dunno. And the improvement comes from reduced
> > dTLB-load-misses? That makes no sense for order-0 buddy struct pages
> > which always share a page. And the memmap mapping should use huge pages.
>
> THP is disabled to stress order 0 pages(should have mentioned this in
> patch's description, sorry about this).
THP isn't related to memmap; the kernel uses huge pages (usually the 1G
pages) in order to map its own memory.
WARNING: multiple messages have this Message-ID (diff)
From: Matthew Wilcox <willy@infradead.org>
To: Aaron Lu <aaron.lu@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Huang Ying <ying.huang@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Kemi Wang <kemi.wang@intel.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Andi Kleen <ak@linux.intel.com>,
Mel Gorman <mgorman@techsingularity.net>,
David Rientjes <rientjes@google.com>
Subject: Re: [PATCH v4 3/3] mm/free_pcppages_bulk: prefetch buddy while not holding lock
Date: Tue, 6 Mar 2018 04:53:04 -0800 [thread overview]
Message-ID: <20180306125303.GA13722@bombadil.infradead.org> (raw)
In-Reply-To: <20180306122733.GA9664@intel.com>
On Tue, Mar 06, 2018 at 08:27:33PM +0800, Aaron Lu wrote:
> On Tue, Mar 06, 2018 at 08:55:57AM +0100, Vlastimil Babka wrote:
> > So the adjacent line prefetch might be disabled? Could you check bios or
> > the MSR mentioned in
> > https://software.intel.com/en-us/articles/disclosure-of-hw-prefetcher-control-on-some-intel-processors
>
> root@lkp-bdw-ep2 ~# rdmsr 0x1a4
> 0
Technically 0x1a4 is per-core, so you should run rdmsr -a 0x1a4 in order to
check all the cores. But I can't imagine they're being set differently on
each core.
> > instructions (calculated from itlb misses and insns-per-itlb-miss) shows
> > less than 1% increase, so dunno. And the improvement comes from reduced
> > dTLB-load-misses? That makes no sense for order-0 buddy struct pages
> > which always share a page. And the memmap mapping should use huge pages.
>
> THP is disabled to stress order 0 pages(should have mentioned this in
> patch's description, sorry about this).
THP isn't related to memmap; the kernel uses huge pages (usually the 1G
pages) in order to map its own memory.
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next prev parent reply other threads:[~2018-03-06 12:53 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 6:28 [PATCH v4 0/3] mm: improve zone->lock scalability Aaron Lu
2018-03-01 6:28 ` Aaron Lu
2018-03-01 6:28 ` [PATCH v4 1/3] mm/free_pcppages_bulk: update pcp->count inside Aaron Lu
2018-03-01 6:28 ` Aaron Lu
2018-03-01 12:11 ` David Rientjes
2018-03-01 12:11 ` David Rientjes
2018-03-01 13:45 ` Michal Hocko
2018-03-01 13:45 ` Michal Hocko
2018-03-12 13:22 ` Vlastimil Babka
2018-03-13 2:11 ` Aaron Lu
2018-03-01 6:28 ` [PATCH v4 2/3] mm/free_pcppages_bulk: do not hold lock when picking pages to free Aaron Lu
2018-03-01 6:28 ` Aaron Lu
2018-03-01 13:55 ` Michal Hocko
2018-03-01 13:55 ` Michal Hocko
2018-03-02 7:15 ` Aaron Lu
2018-03-02 7:15 ` Aaron Lu
2018-03-02 15:34 ` Dave Hansen
2018-03-02 15:34 ` Dave Hansen
2018-03-02 7:31 ` Huang, Ying
2018-03-02 7:31 ` Huang, Ying
2018-03-02 0:01 ` Andrew Morton
2018-03-02 0:01 ` Andrew Morton
2018-03-02 8:01 ` Aaron Lu
2018-03-02 8:01 ` Aaron Lu
2018-03-02 21:23 ` Andrew Morton
2018-03-02 21:23 ` Andrew Morton
2018-03-02 21:25 ` Dave Hansen
2018-03-02 21:25 ` Dave Hansen
2018-03-12 14:22 ` Vlastimil Babka
2018-03-13 3:34 ` Aaron Lu
2018-03-22 15:17 ` Matthew Wilcox
2018-03-26 3:03 ` Aaron Lu
2018-03-01 6:28 ` [PATCH v4 3/3] mm/free_pcppages_bulk: prefetch buddy while not holding lock Aaron Lu
2018-03-01 6:28 ` Aaron Lu
2018-03-01 14:00 ` Michal Hocko
2018-03-01 14:00 ` Michal Hocko
2018-03-02 8:31 ` Aaron Lu
2018-03-02 8:31 ` Aaron Lu
2018-03-02 17:55 ` Vlastimil Babka
2018-03-02 17:55 ` Vlastimil Babka
2018-03-02 18:00 ` Dave Hansen
2018-03-02 18:00 ` Dave Hansen
2018-03-02 18:08 ` Vlastimil Babka
2018-03-02 18:08 ` Vlastimil Babka
2018-03-05 11:41 ` Aaron Lu
2018-03-05 11:41 ` Aaron Lu
2018-03-05 11:48 ` Aaron Lu
2018-03-05 11:48 ` Aaron Lu
2018-03-06 7:55 ` Vlastimil Babka
2018-03-06 7:55 ` Vlastimil Babka
2018-03-06 12:27 ` Aaron Lu
2018-03-06 12:27 ` Aaron Lu
2018-03-06 12:53 ` Matthew Wilcox [this message]
2018-03-06 12:53 ` Matthew Wilcox
2018-03-02 0:09 ` Andrew Morton
2018-03-02 0:09 ` Andrew Morton
2018-03-02 8:27 ` Aaron Lu
2018-03-02 8:27 ` Aaron Lu
2018-03-09 8:24 ` [PATCH v4 3/3 update] " Aaron Lu
2018-03-09 21:58 ` Andrew Morton
2018-03-10 14:46 ` Aaron Lu
2018-03-12 15:05 ` Vlastimil Babka
2018-03-12 17:32 ` Dave Hansen
2018-03-13 3:35 ` Aaron Lu
2018-03-13 7:04 ` Aaron Lu
2018-03-20 9:50 ` Vlastimil Babka
2018-03-20 11:31 ` [PATCH v4 3/3 update2] " Aaron Lu
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