From: Chun Ng <chunn@nvidia.com>
To: Bagas Sanjaya <bagasdotme@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Linux Regressions <regressions@lists.linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
Linux Memory Management List <linux-mm@kvack.org>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Ankita Garg <ankitag@nvidia.com>
Subject: Re: [REGRESSION]: mmap performance regression starting with k-6.1
Date: Thu, 23 Nov 2023 03:06:42 +0000 [thread overview]
Message-ID: <PH7PR12MB79373516F591C102110B4251D6B9A@PH7PR12MB7937.namprd12.prod.outlook.com> (raw)
In-Reply-To: <ZV6oYmVYsyYizvgg@archie.me>
>> Did you mean that v6.0 doesn't have this regression?
No, k-6.0 does NOT have this regression. The regression starts from k-6.1.
Best,
Chun
From: Bagas Sanjaya
Sent: Wednesday, November 22, 2023 5:18 PM
To: Chun Ng; Linux Kernel Mailing List
Cc: Linux Regressions; Andrew Morton; Linux Memory Management List; Liam R. Howlett; Ankita Garg
Subject: Re: [REGRESSION]: mmap performance regression starting with k-6.1
On Wed, Nov 22, 2023 at 08:03:19PM +0000, Chun Ng wrote:
> Hi,
>
> Recently I observed there is performance regression on system call mmap(..). I tried both vanilla kernels and Raspberry Pi kernels on a Raspberry Pi 4 box and the results are pretty consistent among them.
>
> Bisection showed that the regression starts from k-6.1, and the latest vanilla k-6.7 is still showing the same regression.
>
> The test program calls mmap/munmap for a 4K page with MAP_ANON and MAP_PRIVATE flags, and ftrace is used to measure the time spent on the do_mmap(..) call. Measured time of a sample run with different vanilla kernel versions are:
> k-5.10 and k-6.0: ~157us
> k-6.1: ~194us
> k-6.7: ~214us
> Results are pretty consistent across multiple runs with a small percentage variance. Ftrace shows that latency of mmap_region(...) has increased since k-6.1. An application that makes frequent mmap(..) calls the accumulated extra latency is very noticeable.
Did you mean that v6.0 doesn't have this regression?
Confused...
--
An old man doll... just what I always wanted! - Clara
next prev parent reply other threads:[~2023-11-23 3:06 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-22 20:03 [REGRESSION]: mmap performance regression starting with k-6.1 Chun Ng
2023-11-23 1:18 ` Bagas Sanjaya
2023-11-23 3:06 ` Chun Ng [this message]
2023-11-23 5:01 ` Bagas Sanjaya
2023-11-23 5:07 ` Bagas Sanjaya
2023-11-23 8:29 ` David Wang
2023-11-23 14:34 ` Liam R. Howlett
2023-11-24 5:08 ` Linux regression tracking #update (Thorsten Leemhuis)
2023-11-26 7:18 ` David Wang
2023-11-26 13:47 ` Matthew Wilcox
2023-11-23 15:38 ` Matthew Wilcox
2023-11-24 0:15 ` Bagas Sanjaya
2023-11-24 1:04 ` Matthew Wilcox
2023-11-24 11:52 ` Greg KH
2023-11-24 15:06 ` Matthew Wilcox
2023-11-24 15:13 ` Greg KH
2023-11-24 15:29 ` Linux regression tracking (Thorsten Leemhuis)
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