Date: Thu, 6 Mar 2008 07:55:04 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Andriy Gapon <avg@icyb.net.ua> Subject: Re: sched_ule: roundrobin_callout replacement ? Message-ID: <200803060755.04607.jhb@freebsd.org> In-Reply-To: <47B9A359.9080502@icyb.net.ua> References: <47B9A359.9080502@icyb.net.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
On Monday 18 February 2008 10:25:13 am Andriy Gapon wrote: > I see that sched_4bsd has a NOP callout with a purpose of forcing a > context switch (via softclock), so that something like a preemption > could happen (e.g. for threads in a tight calculation loop). > What serves the similar purpose for sched_ule? > Or, how sched_ule deals with the issue without needing softclock's help? It's gone in newer versions of 4BSD in HEAD actually. ULE does it by checking in sched_clock() to see if the current thread has used up its quantum. If so it sets TDF_NEEDRESCHED. -- John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200803060755.04607.jhb>