lkml.org 
[lkml]   [1999]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [rtl] Low-latency patches working GREAT (<2.9ms audio latency), see testresults ,but ISDN troubles
On Sun, Aug 29, 1999 at 09:15:19AM +0200, Ingo Molnar wrote:
>
> On Sat, 28 Aug 1999 yodaiken@fsmlabs.com wrote:
>
> > I'm concerned that the major improvement has come from additional
> > calls to schedule instead of from some basic improvements in algorithm.
>
> there are _no_ extra calls to schedule, only if necessery. Zero, nil,
> nada. Please check out the patch.

Tell me what I misunderstood. As far as I can tell, pre patch behavior
involves many fewer calls to schedule, post patch behavior for a write, for
example, can make at least one extra call to the scheduler for every block
copied. If "needs_resched >0" it is still not necessarily true that the
call to the scheduler is "necessary". Consider, a long running data base
program is writing backing store out to disk. Old behavior: the write
absorbs as much free memory as possible to optimize disk behavior. New
behavior: a screen saver, which is small i/o bound, causes needs resched
to be set continually, and the write is segmented into many smaller writes.
We now have, like NT, optimized the screen saver on a server while hammering
file system performance. Isn't that correct?




-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:53    [from the cache]
©2003-2011 Jasper Spaans