Re: pdflush question...
From: Robert Love
Date: Wed Sep 03 2003 - 12:04:52 EST
On Wed, 2003-09-03 at 05:24, Daniel Blueman wrote:
> Is it worth having a kernel config option to vary the number of 'pdflush'
> kernel threads?
I suspect no.
> For embedded, systems with no swap and maybe uniproc (?), perhaps one
> pdflush kthread would do?
Yes. Definitely. In fact, I think that, for all systems, the initial
default should perhaps be one.
But note that the reason for n>1 pdflush threads is neither swap or
processor related. The multiple threads can keep multiple block devices
busy, since one thread blocking on I/O will not affect another one.
I guess the real test would be to set MIN_PDFLUSH_THREADS to one and see
if one is enough for the average machines. If the number quickly jumps
to 2 or more... then we know its a bad idea.
> Perhaps more generally, the number could be linked to the number of
> processors and/or swap devices or spindles- this would eliminate having to configure
> it, and improve downward and upward scaling, perhaps?
Number of spindles, yes. But how do we know that? And its just the
number of busy spindles, really.
I say we drop down to one.
Robert Love
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