On 06/02/2023 08:28, David Woodhouse wrote:
On Sun, 2023-02-05 at 13:17 -0600, Russ Anderson wrote:
Gave the v6 patchset a try on a system with 1920 logocal cpus
(sixteen 60 core Sapphire Rapids sockets with Hyperthreadding
enabled).
Without the patchset it took 71 seconds to start all the cpus.
With the v6 patchset it took 14 seconds to start all the cpus,
a reduction of 57 seconds. That is impressive.
Full boot, to root login prompt, without patches takes 223 seconds.
This patchset reduces the full boot time by 57 seconds, a 25%
reduction.
Nice; thanks for testing.
Is that with just the "part1" patch series which has been posted, or
also with the 'parallel part 2' still taking shape in the tree at
https://git.infradead.org/users/dwmw2/linux.git/shortlog/refs/heads/parallel-6.2-rc6
I believe Usama said the second phase of parallelism didn't really help
much in terms of overall timing? Confirming that *without* all the
debug prints would be interesting. And we can look for what still
*could* be made parallel.
I think it would be interesting to get the numbers for such a big
machine for 3 cases: part1, part1+reuse timer calibration and part1+part2.
Russ mentioned testing v6, so I guess the above numbers are for
part1+reuse timer calibration.
For my machine the smpboot times were:
No patches: 700ms
part 1:100ms
part1+reuse timer calibration: 30ms
part1+part2: 30ms
Thanks,
Usama
