lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Thu, 23 Nov 2023 03:06:42 +0000
From:   Chun Ng <>
To:     Bagas Sanjaya <>,
        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

>> 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.


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?



An old man doll... just what I always wanted! - Clara

Powered by blists - more mailing lists