Date: Tue, 25 Aug 98 14:17:31 -0500 From: "Richard Seaman, Jr." <lists@tar.com> To: "Garrett Wollman" <wollman@khavrinen.lcs.mit.edu> Cc: "freebsd-current@FreeBSD.ORG" <freebsd-current@FreeBSD.ORG> Subject: Re: Threads across processors Message-ID: <199808251917.OAA28408@ns.tar.com>
next in thread | raw e-mail | index | archive | help
On Tue, 25 Aug 1998 10:10:12 -0400 (EDT), Garrett Wollman wrote:
>I've watched Cyclone hit 150,000 syscalls a SECOND when it's not doing
>much of anything. It's impressive that it can do that, but I'd like
>to have some CPU left over for useful work... Most of those system
>calls were to sigprocmask() to protect some critical section from the
>signals that drive the thred scheduler.
I was under the impression that signal handling in threads was changed
last April to eliminate the sigprocmask calls in the scheduler?
>From uthread_kern.c,v:
"1.10
log
@Change signal model to match POSIX (i.e. one set of signal handlers
for the process, not a separate set for each thread). By default, the
process now only has signal handlers installed for SIGVTALRM, SIGINFO
and SIGCHLD. The thread kernel signal handler is installed for other
signals on demand. This means that SIG_IGN and SIG_DFL processing is now
left to the kernel, not the thread kernel.
Change the signal dispatch to no longer use a signal thread, and
call the signal handler using the stack of the thread that has the
signal pending.
Change the atomic lock method to use test-and-set asm code with
a yield if blocked. This introduces separate locks for each type
of object instead of blocking signals to prevent a context
switch. It was this blocking of signals that caused the performance
degradation the people have noted.
This is a *big* change!"
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199808251917.OAA28408>