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From: Ingo Molnar <mingo@kernel.org>
To: Aaron Lu <aaron.lu@intel.com>
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 11:13:47 +0200	[thread overview]
Message-ID: <20160811091347.GA10990@gmail.com> (raw)
In-Reply-To: <20160811074430.GA18163@aaronlu.sh.intel.com>


* 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:

  3dec0ba0be6a ("mm/rmap: share the i_mmap_rwsem")

I have fixed this in the changelog.

Thanks,

	Ingo

  reply	other threads:[~2016-08-11  9:13 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 [this message]
2016-08-11  9:16   ` Aaron Lu
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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