[lkml]   [2002]   [Feb]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [patch] get_request starvation fix
Rik van Riel wrote:
> On Fri, 8 Feb 2002, Andrew Morton wrote:
> > + * This all assumes that the rate of taking requests is much, much higher
> > + * than the rate of releasing them. Which is very true.
> This is not necessarily true for read requests.
> If each read request is synchronous and the process will
> generate the next read request after the current one
> has finished, then it's quite possible to clog up the
> queue with read requests which are generated at exactly
> the same rate as they're processed.
> Couldn't this still cause starvation, even with your patch?

No, that's fine.

The problem which the comment refers to is: how to provide
per-process request batching without running off and creating
per-process reservation pools or such.

What I'm relying on is that when a sleeper is woken (at low-water),
there are at least (high-water - low-water) requests available before
get_request will again sleep. And that the woken process will be
able to grab a decent number of those non-blocking requests. I
suspect it's always true, as long as (high-water - low_water) is
"much greater than" the number of CPUs.

The synchronous reader is well-behaved, and should be nicely
FIFO if we're getting low on requests.

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 13:24    [W:0.067 / U:0.272 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site