From: Aaron Lu <aaron.lu@intel.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
Alex Shi <alex.shi@linaro.org>,
Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Huang Ying <ying.huang@intel.com>, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] x86/irq: do not substract irq_tlb_count from irq_call_count
Date: Thu, 11 Aug 2016 17:16:49 +0800 [thread overview]
Message-ID: <b750f917-3049-7bb9-11b6-0d9980f8f1e6@intel.com> (raw)
In-Reply-To: <20160811091347.GA10990@gmail.com>
On 08/11/2016 05:13 PM, Ingo Molnar wrote:
>
> * Aaron Lu <aaron.lu@intel.com> wrote:
>
>> This is found by LKP's cyclic performance regression tracking recently
>> with the vm-scalability test suite. I have bisected to commit
>> 0a7ce4b5a632 ("mm/rmap: share the i_mmap_rwsem"). This commit didn't do
>> anything wrong but revealed the irq_call_count problem. IIUC, the commit
>> makes rwc->remap_one in rmap_walk_file concurrent with multiple threads.
>> When remap_one is try_to_unmap_one, then multiple threads could queue
>> flush tlb to the same CPU but only one IPI will be sent.
>
> Note, for some reason the commit ID you used is wrong, the real one is:
Oops, I looked at a test branch where I cherry-picked that commit, sorry.
>
> 3dec0ba0be6a ("mm/rmap: share the i_mmap_rwsem")
>
> I have fixed this in the changelog.
Thanks!
next prev parent reply other threads:[~2016-08-11 9:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-11 7:44 Aaron Lu
2016-08-11 9:13 ` Ingo Molnar
2016-08-11 9:16 ` Aaron Lu [this message]
2016-08-11 11:57 ` [tip:x86/urgent] x86/irq: Do " tip-bot for Aaron Lu
2016-08-11 15:13 ` [PATCH] x86/irq: do " Huang, Ying
2016-08-12 2:16 ` Aaron Lu
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