Re: [Patch 0/9] Performance

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Greg KH wrote:

On Thu, Mar 23, 2006 at 10:16:41AM -0500, Shailabh Nagar wrote:
Greg KH wrote:
On Mon, Mar 13, 2006 at 07:40:34PM -0500, Shailabh Nagar wrote:

This is the next iteration of the delay accounting patches
last posted at
	http://www.ussg.iu.edu/hypermail/linux/kernel/0602.3/0893.html
Do you have any benchmark numbers with this patch applied and with it
not applied?  Last I heard it was a measurable decrease for some
"important" benchmark results...

thanks,

greg k-h
Here are some numbers for the latest set of posted patches
using microbenchmarks hackbench, kernbench and lmbench.

I was trying to get the real/big benchmark numbers too but
it looks like getting a run whose numbers can be trusted
will take a bit longer than expected. Preliminary runs of
transaction processing benchmarks indicate that overhead
actually decreases with the patch (as also seen in some of
the lmbench numbers below).

That's good to hear.

But your .5% is noticable on the +patch results, which I don't think
people who take performance issues seriously will like (that's real
money for the big vendors.)  And distros will be forced to enable that
option in their kernels, so those vendors will have to get that
percentage back some other way...

Sorry, missed your response.

Yes, even the slight deterioration might be an issue for distros. We discovered one memcpy, lack of use of "__read_mostly" and another "unlikely" that might help with the 0.5% but other than that don't see any major way of reducing overhead further for the +patch case.

I'll be posting another iteration of the patches with these changes and corresponding results (as well as the changes for the netlink interface which has been stabilized after incorporating Jamal's
comments). Lets see what that does.

Thanks,
Shailabh

thanks,

greg k-h

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