Subject: Re: Faster pipes, now with uvm_loan()
To: =?iso-8859-1?Q?Jarom=EDr_Dolecek?= <email@example.com>
From: Thor Lancelot Simon <firstname.lastname@example.org>
Date: 04/10/2001 14:52:28
On Tue, Apr 10, 2001 at 04:23:21PM +0200, Jaromír Dolecek wrote:
> BTW, I see the performance drop with hbench too - the bandwidth
> for 128KB transfer size is ~50% of 64KB one on my PIII.
I ran into an issue like this (oh, boy, did I ever!) with CRC-32 in
one of my programs. Doing a whole large buffer at once stomped on all
the cache lines the CRC table (think, the kernel stack or whatever other
might be in the D cache) and code itself (remember, the L2 cache is not
split I/D) was in, causing cache thrashing as the data being worked on
and the "other process state" fought for lines. I bet paring things down
to 64K or even smaller chunks done in a loop will in fact help.
Thor Lancelot Simon email@example.com
And now he couldn't remember when this passion had flown, leaving him so
foolish and bewildered and astray: can any man?