[lkml]   [2002]   [Dec]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Intel P6 vs P7 system call performance
dean gaudet wrote:
> On Mon, 16 Dec 2002, Linus Torvalds wrote:
>>It's not as good as a pure user-mode solution using tsc could be, but
>>we've seen the kinds of complexities that has with multi-CPU systems, and
>>they are so painful that I suspect the sysenter approach is a lot more
>>palatable even if it doesn't allow for the absolute best theoretical
> don't many of the multi-CPU problems with tsc go away because you've got a
> per-cpu physical page for the vsyscall?
> i.e. per-cpu tsc epoch and scaling can be set on that page.
> the only trouble i know of is what happens when an interrupt occurs and
> the task is rescheduled on another cpu... in theory you could test %eip
> against 0xfffffxxx and "rollback" (or complete) any incomplete
> gettimeofday call prior to saving a task's state. but i bet that test is
> undesirable on all interrupt paths.

Exactly. This is a real problem.


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 13:31    [W:0.115 / U:2.384 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site