[lkml]   [2002]   [Sep]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [ANNOUNCE] Native POSIX Thread Library 0.1

On Mon, 23 Sep 2002, Peter Waechtler wrote:

> Getting into kernel is not the same as a context switch. Return EAGAIN
> or EWOULDBLOCK is definetly _not_ causing a context switch.

this is a common misunderstanding. When switching from thread to thread in
the 1:1 model, most of the cost comes from entering/exiting the kernel. So
*once* we are in the kernel the cheapest way is not to piggyback to
userspace to do some userspace context-switch - but to do it right in the

in the kernel we can do much higher quality scheduling decisions than in
userspace. SMP affinity, various statistics are right available in
kernel-space - userspace does not have any of that. Not to talk about


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:29    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean