linux-kernel - RE: SLUB performance regression vs SLAB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <MDEHLPKNGKAHNMBLJOLKOEGOHEAC.davids@webmaster.com>
Date:	Thu, 4 Oct 2007 21:18:24 -0700
From:	"David Schwartz" <davids@...master.com>
To:	<cebbert@...hat.com>
Cc:	<linux-kernel@...r.kernel.org>
Subject: RE: SLUB performance regression vs SLAB

> On 10/04/2007 07:39 PM, David Schwartz wrote:

> > 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.

> People have been trying for years to make reproducible test cases
> for huge and complex workloads. It doesn't work. The tests that do
> work take weeks to run and need to be carefully validated before
> they can be officially released. The open source community can and
> should be working on similar tests, but they will never be simple.

That's true, but irrelevent. Either the test can identify a problem that
applies generally, or it's doing nothing but measuring how good the system
is at doing the test. If the former, it should be possible to create a
simple test case once you know from the complex test where the problem is.
If the latter, who cares about a supposed regression?

It should be possible to identify exactly what portion of the test shows the
regression the most and exactly what the system is doing during that moment.
The test may be great at finding regressions, but once it finds them, they
should be forever *found*.

Did you follow the recent incident when iperf fout what seemed to be a
significnat CFS networking regression? The only way to identify that it was
a quirk in what iperf was doing was by looking at exactly what iperf was
doing. The only efficient way was to look at iperf's source and see that
iperf's weird yielding meant it didn't replicate typical use cases like it
was supposed to.

DS

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/