From: Michal Hocko <mhocko@kernel.org>
To: Shaokun Zhang <zhangshaokun@hisilicon.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, yuqi jin <jinyuqi@huawei.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Paul Burton <paul.burton@mips.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Anshuman Khandual <anshuman.khandual@arm.com>
Subject: Re: [PATCH v2] lib: optimize cpumask_local_spread()
Date: Wed, 6 Nov 2019 10:22:08 +0100 [thread overview]
Message-ID: <20191106092208.GE8314@dhcp22.suse.cz> (raw)
In-Reply-To: <f8f1bce1-4503-4da0-71ea-6fd12fcd687a@hisilicon.com>
On Wed 06-11-19 16:02:29, Shaokun Zhang wrote:
> Hi Michal,
>
> On 2019/11/6 15:17, Michal Hocko wrote:
> > On Tue 05-11-19 17:33:59, Andrew Morton wrote:
> >> On Tue, 5 Nov 2019 08:01:41 +0100 Michal Hocko <mhocko@kernel.org> wrote:
> >>
> >>> On Mon 04-11-19 18:27:48, Shaokun Zhang wrote:
> >>>> From: yuqi jin <jinyuqi@huawei.com>
> >>>>
> >>>> In the multi-processor and NUMA system, I/O device may have many numa
> >>>> nodes belonging to multiple cpus. When we get a local numa, it is
> >>>> better to find the node closest to the local numa node, instead
> >>>> of choosing any online cpu immediately.
> >>>>
> >>>> For the current code, it only considers the local NUMA node and it
> >>>> doesn't compute the distances between different NUMA nodes for the
> >>>> non-local NUMA nodes. Let's optimize it and find the nearest node
> >>>> through NUMA distance. The performance will be better if it return
> >>>> the nearest node than the random node.
> >>>
> >>> Numbers please
> >>
> >> The changelog had
> >>
> >> : When Parameter Server workload is tested using NIC device on Huawei
> >> : Kunpeng 920 SoC:
> >> : Without the patch, the performance is 22W QPS;
> >> : Added this patch, the performance become better and it is 26W QPS.
> >
> > Maybe it is just me but this doesn't really tell me a lot. What is
> > Parameter Server workload? What do I do to replicate those numbers? Is
>
> I will give it better description on it in next version. Since it returns
> the nearest node from the non-local node than the random one, no harmless
> to others, Right?
Well, I am not really familiar with consumers of this API to understand
the full consequences and that is why I keep asking. From a very
highlevel POV prefering CPUs on the same NUMA domain sounds like a
reasonable thing to do.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-11-06 9:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-04 10:27 [PATCH v2] lib: optimize cpumask_local_spread() Shaokun Zhang
2019-11-05 7:01 ` Michal Hocko
2019-11-06 1:33 ` Andrew Morton
2019-11-06 2:49 ` Shaokun Zhang
2019-11-06 7:17 ` Michal Hocko
2019-11-06 8:02 ` Shaokun Zhang
2019-11-06 9:22 ` Michal Hocko [this message]
2019-11-07 1:48 ` Shaokun Zhang
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