Hi Corinna,
Corinna Vinschen wrote:
Hi Christian,
On Nov 25 15:00, Christian Franke wrote:
Corinna Vinschen wrote:
Fixes: ...?
... the very first commit (cgf 2001) of sched.cc :-)
New patch attached.
From e95fc1aceb5287f9ad65c6c078125fecba6c6de9 Mon Sep 17 00:00:00 2001
From: Christian Franke <christian.fra...@t-online.de>
Date: Mon, 25 Nov 2024 14:51:04 +0100
Subject: [PATCH] Cygwin: sched_setscheduler: allow changes of the priority
Behave like sched_setparam() if the requested policy is identical
to the fixed value (SCHED_FIFO) returned by sched_getscheduler().
Fixes: 6b2a2aa4af1e ("Add missing files.")
Huh, yeah, this is spot on. I wonder if it would make sense to change
that to 9a08b2c02eea ("* sched.cc: New file. Implement sched*.")
though, given that was the patch intended to add sched.cc :)))
Sorry, but I have to ask two more questions:
- Isn't returning SCHED_FIFO sched_getscheduler() just as wrong?
Definitly. SCHED_FIFO is a non-preemptive(!) real-time policy. Windows
does not offer anything like that to userland (AFAIK).
https://man7.org/linux/man-pages/man7/sched.7.html
I wonder whether there was a use case for this emulation when this
module was introduced in 2001.
Shouldn't that be SCHED_OTHER, and sched_setscheduler() should check
for that instead? Cygwin in a real-time scenario sounds a bit
far-fetched...
Agree.
Note that SCHED_OTHER requires sched_priority == 0, so most of the
sched_get/set*() priority related code would no longer make sense then.
A related interesting snippet which I don't understand:
sys/sched.h:
#if defined(__CYGWIN__)
#define SCHED_OTHER 3
#else
#define SCHED_OTHER 0
#endif
- Don't you want this patch in 3.5.5? I'd merge the other patch
into 3.5.5 anyway...
OK.
--
Regards,
Christian
