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List:       linux-parisc
Subject:    Re: [PATCH] parisc: Re: [PATCH] parisc: adjust L1_CACHE_BYTES to 128 bytes on PA8800 and PA8900 CPUs
From:       John David Anglin <dave.anglin () bell ! net>
Date:       2015-09-28 20:00:03
Message-ID: 56099C43.70705 () bell ! net
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On 2015-09-28 11:57 AM, Helge Deller wrote:
> Hi Dave,
> 
> On 27.09.2015 18:27, John David Anglin wrote:
> > On 2015-09-22, at 12:20 PM, Helge Deller wrote:
> > > The baseline for all results is the timing with a vanilla kernel 4.2:
> > > real    0m13.596s
> > > user    0m18.152s
> > > sys     0m35.752s
> > > 
> > > 
> > > The next results are with the atomic_hash (a) patch applied:
> > > For ATOMIC_HASH_SIZE = 4.
> > > real    0m21.892s
> > > user    0m27.492s
> > > sys     0m59.704s
> > > 
> > > For ATOMIC_HASH_SIZE = 64.
> > > real    0m20.604s
> > > user    0m24.832s
> > > sys     0m56.552s
> > > 
> > Attached is a revised patch "a" to try to improve performance of atomic_t \
> > variables.  If you get a chance, could you see how it performs.
> here are the numbers for your revised "a" patch (on top of vanilla kernel 4.2):
> 
> real    0m20.040s
> user    0m22.876s
> sys     0m56.724s
> (Variations can be around +- 0.5 seconds)
> 
> If you want to test yourself:
> The testcase executable is on sibaris: \
> /home/var_lib_sbuild_build/libatomic/libatomic-ops-7.4.2/test_atomic
It doesn't seem like the padding has much difference.  I had hoped for 
better although
the test probably doesn't test atomic_t variables.  The regression from 
the the vanilla
kernel is a problem.

Dave

-- 
John David Anglin  dave.anglin@bell.net

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