On 01/16/2012 07:53 PM, Alexander Graf wrote:
On 16.01.2012, at 15:20, Srivatsa Vaddagiri wrote:
* Alexander Graf<agraf@xxxxxxx> [2012-01-16 04:57:45]:
Speaking of which - have you benchmarked performance degradation of pv ticket locks on bare metal?
You mean, run kernel on bare metal with CONFIG_PARAVIRT_SPINLOCKS
enabled and compare how it performs with CONFIG_PARAVIRT_SPINLOCKS disabled for
some workload(s)?
Yup
In some sense, the 1x overcommitcase results posted does measure the overhead
of (pv-)spinlocks no? We don't see any overhead in that case for atleast
kernbench ..
Result for Non PLE machine :
============================
[snip]
Kernbench:
BASE BASE+patch
What is BASE really? Is BASE already with the PV spinlocks enabled? I'm having a hard time understanding which tree you're working against, since the prerequisites aren't upstream yet.
Alex
Sorry for confusion, I think I was little imprecise on the BASE.
The BASE is pre 3.2.0 + Jeremy's following patches:
xadd (https://lkml.org/lkml/2011/10/4/328)
x86/ticketlocklock (https://lkml.org/lkml/2011/10/12/496).
So this would have ticketlock cleanups from Jeremy and
CONFIG_PARAVIRT_SPINLOCKS=y
BASE+patch = pre 3.2.0 + Jeremy's above patches + above V5 PV spinlock
series and CONFIG_PARAVIRT_SPINLOCKS=y
In both the cases CONFIG_PARAVIRT_SPINLOCKS=y.
So let,
A. pre-3.2.0 with CONFIG_PARAVIRT_SPINLOCKS = n
B. pre-3.2.0 + Jeremy's above patches with CONFIG_PARAVIRT_SPINLOCKS = n
C. pre-3.2.0 + Jeremy's above patches with CONFIG_PARAVIRT_SPINLOCKS = y
D. pre-3.2.0 + Jeremy's above patches + V5 patches with
CONFIG_PARAVIRT_SPINLOCKS = n
E. pre-3.2.0 + Jeremy's above patches + V5 patches with
CONFIG_PARAVIRT_SPINLOCKS = y
is it performance of A vs E ? (currently C vs E)
Please let me know the configuration expected for testing.
Jeremy,
I would be happy to test A vs B vs C vs E, for some workload of interest
if you wish, for your upcoming patches.
Thanks and Regards
Raghu
%improvement
mean (sd) mean (sd)
Scenario A:
case 1x: 164.233 (16.5506) 163.584 (15.4598 0.39517
[snip]
Result for PLE machine:
======================
[snip]
Kernbench:
BASE BASE+patch
%improvement
mean (sd) mean (sd)
Scenario A:
case 1x: 161.263 (56.518) 159.635 (40.5621) 1.00953
- vatsa
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