From: kemi <kemi.wang@intel.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
Johannes Weiner <hannes@cmpxchg.org>,
Christopher Lameter <cl@linux.com>,
YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Nikolay Borisov <nborisov@suse.com>,
Pavel Tatashin <pasha.tatashin@oracle.com>,
David Rientjes <rientjes@google.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Dave <dave.hansen@linux.intel.com>,
Andi Kleen <andi.kleen@intel.com>,
Tim Chen <tim.c.chen@intel.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Ying Huang <ying.huang@intel.com>, Aaron Lu <aaron.lu@intel.com>,
Aubrey Li <aubrey.li@intel.com>, Linux MM <linux-mm@kvack.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 3/5] mm: enlarge NUMA counters threshold size
Date: Thu, 21 Dec 2017 18:31:19 +0800 [thread overview]
Message-ID: <10bf5ed1-77f0-281b-dde5-282879e87c39@intel.com> (raw)
In-Reply-To: <20171221085952.GB4831@dhcp22.suse.cz>
On 2017年12月21日 16:59, Michal Hocko wrote:
> On Thu 21-12-17 16:23:23, kemi wrote:
>>
>>
>> On 2017年12月21日 16:17, Michal Hocko wrote:
> [...]
>>> Can you see any difference with a more generic workload?
>>>
>>
>> I didn't see obvious improvement for will-it-scale.page_fault1
>> Two reasons for that:
>> 1) too long code path
>> 2) server zone lock and lru lock contention (access to buddy system frequently)
>
> OK. So does the patch helps for anything other than a microbenchmark?
>
>>>> Some thinking about that:
>>>> a) the overhead due to cache bouncing caused by NUMA counter update in fast path
>>>> severely increase with more and more CPUs cores
>>>
>>> What is an effect on a smaller system with fewer CPUs?
>>>
>>
>> Several CPU cycles can be saved using single thread for that.
>>
>>>> b) AFAIK, the typical usage scenario (similar at least)for which this optimization can
>>>> benefit is 10/40G NIC used in high-speed data center network of cloud service providers.
>>>
>>> I would expect those would disable the numa accounting altogether.
>>>
>>
>> Yes, but it is still worthy to do some optimization, isn't?
>
> Ohh, I am not opposing optimizations but you should make sure that they
> are worth the additional code and special casing. As I've said I am not
> convinced special casing numa counters is good. You can play with the
> threshold scaling for larger CPU count but let's make sure that the
> benefit is really measurable for normal workloads. Special ones will
> disable the numa accounting anyway.
>
I understood. Could you give me some suggestion for those normal workloads, Thanks.
I will have a try and post the data ASAP.
next prev parent reply other threads:[~2017-12-21 10:33 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-19 6:39 [PATCH v2 0/5] mm: NUMA stats code cleanup and enhancement Kemi Wang
2017-12-19 6:39 ` [PATCH v2 1/5] mm: migrate NUMA stats from per-zone to per-node Kemi Wang
2017-12-19 12:28 ` Michal Hocko
2017-12-20 5:32 ` kemi
2017-12-19 6:39 ` [PATCH v2 2/5] mm: Extends local cpu counter vm_diff_nodestat from s8 to s16 Kemi Wang
2017-12-19 12:38 ` Michal Hocko
2017-12-20 3:05 ` kemi
2017-12-19 16:05 ` Christopher Lameter
2017-12-19 16:20 ` Michal Hocko
2017-12-19 17:21 ` Christopher Lameter
2017-12-20 6:45 ` kemi
2017-12-19 6:39 ` [PATCH v2 3/5] mm: enlarge NUMA counters threshold size Kemi Wang
2017-12-19 12:40 ` Michal Hocko
2017-12-20 5:52 ` kemi
2017-12-20 10:12 ` Michal Hocko
2017-12-20 10:21 ` kemi
2017-12-21 8:06 ` kemi
2017-12-21 8:17 ` Michal Hocko
2017-12-21 8:23 ` kemi
2017-12-21 8:59 ` Michal Hocko
2017-12-21 10:31 ` kemi [this message]
2017-12-22 12:31 ` Michal Hocko
2017-12-21 17:10 ` Christopher Lameter
2017-12-22 2:06 ` kemi
2017-12-26 19:05 ` Christopher Lameter
2017-12-19 6:39 ` [PATCH v2 4/5] mm: use node_page_state_snapshot to avoid deviation Kemi Wang
2017-12-19 12:43 ` Michal Hocko
2017-12-20 6:07 ` kemi
2017-12-20 10:06 ` Michal Hocko
2017-12-20 10:24 ` kemi
2017-12-20 15:58 ` Christopher Lameter
2017-12-21 1:39 ` kemi
2017-12-19 6:39 ` [PATCH v2 5/5] mm: Rename zone_statistics() to numa_statistics() Kemi Wang
2017-12-19 12:44 ` Michal Hocko
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