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Subject: Re: [LKP] [mm] 9bc8039e71: will-it-scale.per_thread_ops -64.1%
 regression
To:     Tim Chen <tim.c.chen@linux.intel.com>,
        "Wang, Kemi" <kemi.wang@intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "vbabka@suse.cz" <vbabka@suse.cz>,
        Davidlohr Bueso <dave@stgolabs.net>
Cc:     "yang.shi@linux.alibaba.com" <yang.shi@linux.alibaba.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        "mhocko@kernel.org" <mhocko@kernel.org>,
        Colin King <colin.king@canonical.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "ldufour@linux.vnet.ibm.com" <ldufour@linux.vnet.ibm.com>,
        "lkp@01.org" <lkp@01.org>,
        "kirill.shutemov@linux.intel.com" <kirill.shutemov@linux.intel.com>
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From:   Waiman Long <longman@redhat.com>
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Message-ID: <02602a13-e6f1-dfc1-48b6-1cb14bd9dfd0@redhat.com>
Date:   Wed, 30 Jan 2019 21:54:15 -0500
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On 01/30/2019 07:06 PM, Tim Chen wrote:
> On 12/27/18 6:55 PM, Waiman Long wrote:
>> On 12/27/2018 08:31 PM, Wang, Kemi wrote:
>>> Hi, Waiman
>>>    Did you post that patch? Let's see if it helps.
>> I did post the patch a while ago. I will need to rebase it to a new
>> baseline. Will do that in a week or 2.
>>
>> -Longman
>>
> Waiman,
>
> In a large scale OLTP benchmark, we are also seeing a 1% loss in performance
> from patch 9bc8039e71. We'll be interested to try out your patch to
> restore some optimistic spinning on reader held sem.
>
> Thanks.
>
> Tim

I am reworking the rwsem code and reader-optimistic spinning code isn't
ready with the reworked code yet. I need a bit more time to work on that
and certainly keep you posted once it is ready for review.

Cheers,
Longman