Messages in this thread | | | Subject | Re: [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code | From | Alexandre Chartre <> | Date | Wed, 18 Nov 2020 20:37:57 +0100 |
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On 11/18/20 12:29 PM, Borislav Petkov wrote: > On Wed, Nov 18, 2020 at 08:41:42AM +0100, Alexandre Chartre wrote: >> Well, it looks like I wrongfully assume that KPTI was a well known performance >> overhead since it was introduced (because it adds extra page-table switches), >> but you are right I should be presenting my own numbers. > > Here's one recipe, courtesy of Mel: > > https://github.com/gormanm/mmtests >
Thanks for the detailed information, I have run the test and I see the same difference as with the tools/perf and libMICRO I already sent: there's a 150% difference for getpid() with and without pti.
alex.
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# ../../compare-kernels.sh --baseline test-nopti --compare test-pti
poundsyscall test test nopti pti Min 2 1.99 ( 0.00%) 5.08 (-155.28%) Min 4 1.02 ( 0.00%) 2.60 (-154.90%) Min 6 0.94 ( 0.00%) 2.07 (-120.21%) Min 8 0.81 ( 0.00%) 1.60 ( -97.53%) Min 12 0.85 ( 0.00%) 1.65 ( -94.12%) Min 18 0.82 ( 0.00%) 1.61 ( -96.34%) Min 24 0.81 ( 0.00%) 1.60 ( -97.53%) Min 30 0.81 ( 0.00%) 1.60 ( -97.53%) Min 32 0.81 ( 0.00%) 1.60 ( -97.53%) Amean 2 2.02 ( 0.00%) 5.10 *-151.83%* Amean 4 1.03 ( 0.00%) 2.61 *-151.98%* Amean 6 0.96 ( 0.00%) 2.07 *-116.74%* Amean 8 0.82 ( 0.00%) 1.60 * -96.56%* Amean 12 0.87 ( 0.00%) 1.67 * -91.73%* Amean 18 0.82 ( 0.00%) 1.63 * -97.94%* Amean 24 0.81 ( 0.00%) 1.60 * -97.41%* Amean 30 0.82 ( 0.00%) 1.60 * -96.93%* Amean 32 0.82 ( 0.00%) 1.60 * -96.56%* Stddev 2 0.02 ( 0.00%) 0.02 ( 33.78%) Stddev 4 0.01 ( 0.00%) 0.01 ( 7.18%) Stddev 6 0.01 ( 0.00%) 0.00 ( 68.77%) Stddev 8 0.01 ( 0.00%) 0.01 ( 10.56%) Stddev 12 0.01 ( 0.00%) 0.02 ( -12.69%) Stddev 18 0.01 ( 0.00%) 0.01 (-107.25%) Stddev 24 0.00 ( 0.00%) 0.00 ( -14.56%) Stddev 30 0.01 ( 0.00%) 0.01 ( 0.00%) Stddev 32 0.01 ( 0.00%) 0.00 ( 20.00%) CoeffVar 2 1.17 ( 0.00%) 0.31 ( 73.70%) CoeffVar 4 0.82 ( 0.00%) 0.30 ( 63.16%) CoeffVar 6 1.41 ( 0.00%) 0.20 ( 85.59%) CoeffVar 8 0.87 ( 0.00%) 0.39 ( 54.50%) CoeffVar 12 1.66 ( 0.00%) 0.98 ( 41.23%) CoeffVar 18 0.85 ( 0.00%) 0.89 ( -4.71%) CoeffVar 24 0.52 ( 0.00%) 0.30 ( 41.97%) CoeffVar 30 0.65 ( 0.00%) 0.33 ( 49.22%) CoeffVar 32 0.65 ( 0.00%) 0.26 ( 59.30%) Max 2 2.04 ( 0.00%) 5.13 (-151.47%) Max 4 1.04 ( 0.00%) 2.62 (-151.92%) Max 6 0.98 ( 0.00%) 2.08 (-112.24%) Max 8 0.83 ( 0.00%) 1.62 ( -95.18%) Max 12 0.89 ( 0.00%) 1.70 ( -91.01%) Max 18 0.84 ( 0.00%) 1.66 ( -97.62%) Max 24 0.82 ( 0.00%) 1.61 ( -96.34%) Max 30 0.82 ( 0.00%) 1.61 ( -96.34%) Max 32 0.82 ( 0.00%) 1.61 ( -96.34%) BAmean-50 2 2.01 ( 0.00%) 5.09 (-153.39%) BAmean-50 4 1.03 ( 0.00%) 2.60 (-152.62%) BAmean-50 6 0.95 ( 0.00%) 2.07 (-118.82%) BAmean-50 8 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-50 12 0.86 ( 0.00%) 1.66 ( -92.79%) BAmean-50 18 0.82 ( 0.00%) 1.62 ( -97.56%) BAmean-50 24 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-50 30 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-50 32 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-95 2 2.02 ( 0.00%) 5.09 (-151.87%) BAmean-95 4 1.03 ( 0.00%) 2.61 (-151.99%) BAmean-95 6 0.95 ( 0.00%) 2.07 (-117.25%) BAmean-95 8 0.81 ( 0.00%) 1.60 ( -96.72%) BAmean-95 12 0.87 ( 0.00%) 1.67 ( -91.82%) BAmean-95 18 0.82 ( 0.00%) 1.63 ( -97.97%) BAmean-95 24 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-95 30 0.81 ( 0.00%) 1.60 ( -97.00%) BAmean-95 32 0.81 ( 0.00%) 1.60 ( -96.59%) BAmean-99 2 2.02 ( 0.00%) 5.09 (-151.87%) BAmean-99 4 1.03 ( 0.00%) 2.61 (-151.99%) BAmean-99 6 0.95 ( 0.00%) 2.07 (-117.25%) BAmean-99 8 0.81 ( 0.00%) 1.60 ( -96.72%) BAmean-99 12 0.87 ( 0.00%) 1.67 ( -91.82%) BAmean-99 18 0.82 ( 0.00%) 1.63 ( -97.97%) BAmean-99 24 0.81 ( 0.00%) 1.60 ( -97.53%) BAmean-99 30 0.81 ( 0.00%) 1.60 ( -97.00%) BAmean-99 32 0.81 ( 0.00%) 1.60 ( -96.59%)
test test nopti pti Duration User 150.13 432.03 Duration System 372.10 657.69 Duration Elapsed 94.17 199.27
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