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From: Yaohui Wang <yaohuiwang@linux.alibaba.com>
To: Dave Hansen <dave.hansen@intel.com>, tglx@linutronix.de
Cc: luto@kernel.org, peterz@infradead.org, mingo@redhat.com,
	bp@alien8.de, x86@kernel.org, linux-kernel@vger.kernel.org,
	luoben@linux.alibaba.com, Tom Lendacky <thomas.lendacky@amd.com>,
	Brijesh Singh <brijesh.singh@amd.com>
Subject: Re: [PATCH v3 1/2] x86/ioremap: fix the pfn calculation mistake in __ioremap_check_ram()
Date: Fri, 2 Jul 2021 18:05:02 +0800	[thread overview]
Message-ID: <34bae667-180f-ce97-ee55-12e13ff28ca0@linux.alibaba.com> (raw)
In-Reply-To: <94a38542-b639-37e4-1b53-29b59c5ea655@intel.com>



On 2021/7/1 22:41, Dave Hansen wrote:
> Was this issue found by inspection, or is it causing an actual problem
> in practice?

This issus truly caused terrible perforamnce downgrade in the practice.
When developing an out of tree module in our testing environment,
invoking ioremap() on normal RAM causes apparent CLI lag. The Unixbench
score also decreases a lot (5x slowdown in the worst case).

Debugging such performance issue is extremely difficult, especially when
the code of the faulty module itself is already very complex. I tested
the system in many aspects before finally located this problem.

> Also, it would be really nice to include the original authors when you
> send Fixes: for patches.  BTW, scripts/get_maintainer.pl would have done
> this for you.  I've added Tom and Brijesh.  Please cc them in the future.

I'll pay attention to this in the future. Thank you for your time and
patience!

  reply	other threads:[~2021-07-02 10:05 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-21 12:34 [PATCH v3 0/2] x86/ioremap: fix boundary calculation and boundary judgment issues for ioremap() Yaohui Wang
2021-06-21 12:34 ` [PATCH v3 1/2] x86/ioremap: fix the pfn calculation mistake in __ioremap_check_ram() Yaohui Wang
2021-07-01 14:41   ` Dave Hansen
2021-07-02 10:05     ` Yaohui Wang [this message]
2021-07-02 14:49       ` Dave Hansen
2021-07-05  2:11         ` Yaohui Wang
2021-06-21 12:34 ` [PATCH v3 2/2] kernel/resource: fix boundary judgment issues in find_next_iomem_res() and __walk_iomem_res_desc() Yaohui Wang
2021-07-01 16:29   ` Dave Hansen
2021-07-01  2:44 ` [PATCH v3 0/2] x86/ioremap: fix boundary calculation and boundary judgment issues for ioremap() Yaohui Wang

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