Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: hackbench regression due to commit 9dfc6e68bfe6e | From | "Zhang, Yanmin" <> | Date | Fri, 02 Apr 2010 16:06:29 +0800 |
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On Thu, 2010-04-01 at 10:53 -0500, Christoph Lameter wrote: > On Thu, 1 Apr 2010, Zhang, Yanmin wrote: > > > I suspect the moving of place of cpu_slab in kmem_cache causes the new cache > > miss. But when I move it to the tail of the structure, kernel always panic when > > booting. Perhaps there is another potential bug? > > Why would that cause an additional cache miss? > > > The node array is following at the end of the structure. If you want to > move it down then it needs to be placed before the node field
Thanks. The moving cpu_slab to tail doesn't improve it.
I used perf to collect statistics. Only data cache miss has a little difference. My testing command on my 2 socket machine: #hackbench 100 process 20000
With 2.6.33, it takes for about 96 seconds while 2.6.34-rc2 (or the latest tip tree) takes for about 101 seconds.
perf shows some functions around SLUB have more cpu utilization, while some other SLUB functions have less cpu utilization.
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