Re: [Lse-tech] Re: (RFC): SKB Initialization

[William Lee Irwin III]

On Thu, Aug 22, 2002 at 12:02:27PM -0700, Dave Hansen wrote:
> You can see the entire readprofile here:
> http://www.sr71.net/~specweb99/run-specweb-100sec-2400-2.5.31-bk+4-kmap-08-22-2002-11.20.17/
> http://www.sr71.net/~specweb99/run-specweb-100sec-2400-2.5.31-bk+4-kmap-mala-08-22-2002-11.44.25/
> No, I don't know why I have so much idle time.

Hmm, I found that tiobench was spending a lot of time idle due to
__wait_on_inode() and get_request_wait(). I bumped up the size of
the inode wait table to 1024 and the request queue size to 16384
and saw that most of them then spent their time stuck on ->i_sem
during the initial open of the file they were going to pound on
for the duration of the run.

I determined this by just ^C'ing with kgdb and backtracing various
"stuck" processes. I think various profiling patches might be able to
give you an idea of what people are going to sleep on too.

Cheers,
Bill