On 2026-08-19 18:43:34 +0100, Ian Collier via Mutt-dev wrote: > On modern systems HZ=1000, but my testing showed a delay of up to 1.53ms > on x86_64 and 1.08ms on arm64.
A correction on this: Under Linux, the time(7) man page says: The value of HZ varies across kernel versions and hardware platforms. On i386 the situation is as follows: on kernels up to and including Linux 2.4.x, HZ was 100, giving a jiffy value of 0.01 seconds; starting with Linux 2.6.0, HZ was raised to 1000, giving a jiffy of 0.001 seconds. Since Linux 2.6.13, the HZ value is a kernel configuration parameter and can be 100, 250 (the default) or 1000, yielding a jiffies value of, respectively, 0.01, 0.004, or 0.001 seconds. Since Linux 2.6.20, a further frequency is available: 300, a number that divides evenly for the common video frame rates (PAL, 25 Hz; NTSC, 30 Hz). So most Linux users would expect HZ=250 (a jiffy of 0.004 s = 4 ms). This is my case: qaa:~> grep '^CONFIG_HZ=' /boot/config-$(uname -r) CONFIG_HZ=250 BTW, I can reproduce the issue with qaa:~> /usr/bin/stat /var/tmp/mutt-qaa-1000-* File: /var/tmp/mutt-qaa-1000-2882-16034754240795970957 Size: 227 Blocks: 8 IO Block: 4096 regular file Device: 254,1 Inode: 13252683 Links: 1 Access: (0600/-rw-------) Uid: ( 1000/ vinc17) Gid: ( 1000/ vinc17) Access: 2026-08-20 10:10:25.003735485 +0200 Modify: 2026-08-20 10:10:25.003700613 +0200 Change: 2026-08-20 10:10:25.003700613 +0200 Birth: 2026-08-20 10:10:25.003367902 +0200 0.003700613 is a little less than the 0.004 s jiffy. So I would expect the issue to occur with a frequency of about 1/250. -- Vincent Lefèvre <[email protected]> - Web: <https://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)
