On Sun, 2020-03-01 at 09:24 +0800, Ian Campbell wrote: > On Sat, 2020-02-29 at 20:14 +0100, Harald Dunkel wrote: > > Hi folks, > > > > looking at the number of cores and highly parallel applications > > I wonder if it would be reasonable to increase the default > > kernel.pid_max (currently 0x8000) to lets say 0x3fffff? > > > > Do you expect negative side effects? > > It's already 0x400000 on my machine and everything is fine. I haven't > (knowingly) tweaked anything so I guess this is the default on recent > machines, this laptop is running 5.4.0-3-amd64 (testing userspace, > although not updated for a little bit). > > I can't actually find when/where this changed in recent history -- I've > only noticed these large pids in recent months, but it's entirely > possible I'm simply not that observant.
This was a change in systemd 243:
* On 64 bit systems, the "kernel.pid_max" sysctl is now bumped to
4194304 by default, i.e. the full 22bit range the kernel allows, up
from the old 16bit range.
Ben.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=72680a191b934377430032f93af15ef50aafb3a8
> was in 2010 and a 2.6.x
> kernel.
>
> Ian.
>
--
Ben Hutchings
It is a miracle that curiosity survives formal education.
- Albert Einstein
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