RE: SLUB performance regression vs SLAB

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To: Linux-Kernel@Vger. Kernel. Org <linux-kernel@...>
Date: Thursday, October 4, 2007 - 7:39 pm

David Miller wrote:


I would just like to echo what you said just a bit angrier. This is the same
as someone asking him to fix a bug that they can only see with a binary-only
kernel module. I think he's perfectly justified in simply responding "the
bug is as likely to be in your code as mine".

Now, just because he's justified in doing that doesn't mean he should. I
presume he has an honest desire to improve his own code and if they've found
a real problem, I'm sure he'd love to fix it.

But this is just a preposterous position to put him in. If there's no
reproduceable test case, then why should he care that one program he can't
even see works badly? If you care, you fix it.

Matthew Wilcox wrote:


It means it may or may not exist. All we have is your word that slub is the
problem. If I said I found a bug in the Linux kernel that caused it to panic
but I could only reproduce it with the nVidia driver, I'd be laughed at.

It may even be that slub is better, your benchmark simply interprets this as
worse. Without the details of your benchmark, we can't know. For example,
I've seen benchmarks that (usually unintentionally) actually do a *variable*
amount of work and details of the implementation may result in the benchmark
actually doing *more* work, so it taking longer does not mean it ran slower.

DS


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Messages in current thread:
[15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Tue Sep 18, 11:36 pm)
Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Fri Sep 28, 1:33 pm)
Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Mon Oct 1, 4:50 pm)
SLUB performance regression vs SLAB, Matthew Wilcox, (Thu Oct 4, 12:16 pm)
Re: SLUB performance regression vs SLAB, Christoph Lameter, (Thu Oct 4, 1:38 pm)
Re: SLUB performance regression vs SLAB, Arjan van de Ven, (Thu Oct 4, 1:50 pm)
Re: SLUB performance regression vs SLAB, David Miller, (Thu Oct 4, 4:48 pm)
RE: SLUB performance regression vs SLAB, David Schwartz, (Thu Oct 4, 7:39 pm)
Re: SLUB performance regression vs SLAB, Chuck Ebbert, (Thu Oct 4, 7:49 pm)
RE: SLUB performance regression vs SLAB, David Schwartz, (Fri Oct 5, 12:18 am)
Re: SLUB performance regression vs SLAB, Matthew Wilcox, (Thu Oct 4, 4:58 pm)
Re: SLUB performance regression vs SLAB, Christoph Lameter, (Thu Oct 4, 5:11 pm)
Re: SLUB performance regression vs SLAB, David Miller, (Thu Oct 4, 5:05 pm)
Re: SLUB performance regression vs SLAB, Peter Zijlstra, (Thu Oct 4, 2:26 pm)
Re: SLUB performance regression vs SLAB, Christoph Lameter, (Thu Oct 4, 1:58 pm)
Re: SLUB performance regression vs SLAB, Matthew Wilcox, (Thu Oct 4, 2:32 pm)
Re: SLUB performance regression vs SLAB, Christoph Lameter, (Thu Oct 4, 1:49 pm)
Re: SLUB performance regression vs SLAB, Matthew Wilcox, (Thu Oct 4, 3:28 pm)
Re: SLUB performance regression vs SLAB, David Miller, (Thu Oct 4, 4:55 pm)
Re: SLUB performance regression vs SLAB, Chuck Ebbert, (Thu Oct 4, 5:02 pm)
Re: SLUB performance regression vs SLAB, Peter Zijlstra, (Fri Oct 5, 4:32 pm)
Re: SLUB performance regression vs SLAB, David Miller, (Fri Oct 5, 5:31 pm)
Re: SLUB performance regression vs SLAB, David Miller, (Thu Oct 4, 5:11 pm)
Re: SLUB performance regression vs SLAB, Chuck Ebbert, (Thu Oct 4, 5:47 pm)
Re: SLUB performance regression vs SLAB, David Miller, (Thu Oct 4, 6:07 pm)
Re: SLUB performance regression vs SLAB, David Chinner, (Thu Oct 4, 6:23 pm)
Re: SLUB performance regression vs SLAB, Jens Axboe, (Fri Oct 5, 2:48 am)
Re: SLUB performance regression vs SLAB, Matthew Wilcox, (Fri Oct 5, 7:56 am)
Re: SLUB performance regression vs SLAB, Christoph Lameter, (Fri Oct 5, 3:27 pm)
Re: SLUB performance regression vs SLAB, Jens Axboe, (Fri Oct 5, 8:37 am)
Re: SLUB performance regression vs SLAB, Pekka Enberg, (Fri Oct 5, 5:19 am)
Re: SLUB performance regression vs SLAB, Jens Axboe, (Fri Oct 5, 5:28 am)
Re: SLUB performance regression vs SLAB, Andi Kleen, (Fri Oct 5, 7:12 am)
Re: SLUB performance regression vs SLAB, Jens Axboe, (Fri Oct 5, 8:39 am)
Re: SLUB performance regression vs SLAB, Christoph Lameter, (Fri Oct 5, 3:31 pm)
Re: SLUB performance regression vs SLAB, Christoph Lameter, (Fri Oct 5, 3:32 pm)
Re: SLUB performance regression vs SLAB, Matthew Wilcox, (Thu Oct 4, 5:05 pm)
Re: SLUB performance regression vs SLAB, Christoph Lameter, (Thu Oct 4, 10:43 pm)
Re: SLUB performance regression vs SLAB, Arjan van de Ven, (Thu Oct 4, 10:53 pm)
Re: SLUB performance regression vs SLAB, Christoph Lameter, (Thu Oct 4, 3:05 pm)
Re: SLUB performance regression vs SLAB, Siddha, Suresh B, (Thu Oct 4, 3:46 pm)
Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Mon Oct 1, 5:10 pm)
Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Fri Sep 28, 2:20 pm)
Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Mon Oct 1, 5:01 pm)
Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Mon Oct 1, 4:55 pm)
Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Mon Oct 1, 5:38 pm)
Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Mon Oct 1, 5:52 pm)
Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK, Christoph Lameter, (Fri Sep 28, 2:41 pm)