On 06/28/2011 01:58 PM, David Rientjes wrote:
On Tue, 28 Jun 2011, David Daney wrote:
On 06/28/2011 12:32 PM, Christoph Lameter wrote:
On Sun, 26 Jun 2011, Marcin Slusarz wrote:
slub checks for poison one byte by one, which is highly inefficient
and shows up frequently as a highest cpu-eater in perf top.
Ummm.. Performance improvements for debugging modes? If you need
performance then switch off debuggin.
There is no reason to make things gratuitously slow. I don't know about the
merits of this particular patch, but I must disagree with the general
sentiment.
We have high performance tracing, why not improve this as well.
Just last week I was trying to find the cause of memory corruption that only
occurred at very high network packet rates. Memory allocation speed was
definitely getting in the way of debugging. For me, faster SLUB debugging
would be welcome.
SLUB debugging is useful only to diagnose issues or test new code, nobody
is going to be enabling it in production environment. We don't need 30
new lines of code that make one thing slightly faster, in fact we'd prefer
to have as simple and minimal code as possible for debugging features
unless you're adding more debugging coverage.
If your problem happens under load, then the overhead of slub could significantly
change the behaviour of the system. Anything that makes it more efficient without
unduly complicating code should be a win. That posted patch wasn't all that
complicated, and even if it has bugs, it could be fixed easily enough.
Thanks,
Ben
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Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
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