linux-kernel - Re: [PATCH v4.16-rc5 (2)] x86/vdso: VDSO should handle clock_gettime(CLOCK_MONOTONIC

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Message-ID: <CALyZvKycERiszrH2k=HbdQSn4tWhFQKYpUvW-TKpKfX6D1BUmA@mail.gmail.com>
Date:   Sat, 17 Mar 2018 23:37:39 +0000
From:   Jason Vas Dias <jason.vas.dias@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
        x86@...nel.org, mingo@...nel.org, peterz@...radead.org,
        andi@...stfloor.org
Subject: Re: [PATCH v4.16-rc5 (2)] x86/vdso: VDSO should handle
 clock_gettime(CLOCK_MONOTONIC_RAW) without syscall

fixed typo in timer_latency.c affecting only -r <repeat> printout
:

$ gcc -DN_SAMPLES=1000 -o timer timer_latency.c
CLOCK_MONOTONIC ( using rdtscp_ordered() ) :

$ ./timer -m -r 10
sum: 67615
Total time: 0.000067615S - Average Latency: 0.000000067S N zero
deltas: 0 N inconsistent deltas: 0
sum: 51858
Total time: 0.000051858S - Average Latency: 0.000000051S N zero
deltas: 0 N inconsistent deltas: 0
sum: 51742
Total time: 0.000051742S - Average Latency: 0.000000051S N zero
deltas: 0 N inconsistent deltas: 0
sum: 51944
Total time: 0.000051944S - Average Latency: 0.000000051S N zero
deltas: 0 N inconsistent deltas: 0
sum: 51838
Total time: 0.000051838S - Average Latency: 0.000000051S N zero
deltas: 0 N inconsistent deltas: 0
sum: 52397
Total time: 0.000052397S - Average Latency: 0.000000052S N zero
deltas: 0 N inconsistent deltas: 0
sum: 52428
Total time: 0.000052428S - Average Latency: 0.000000052S N zero
deltas: 0 N inconsistent deltas: 0
sum: 52135
Total time: 0.000052135S - Average Latency: 0.000000052S N zero
deltas: 0 N inconsistent deltas: 0
sum: 52145
Total time: 0.000052145S - Average Latency: 0.000000052S N zero
deltas: 0 N inconsistent deltas: 0
sum: 53116
Total time: 0.000053116S - Average Latency: 0.000000053S N zero
deltas: 0 N inconsistent deltas: 0
Average of 10 average latencies of 1000 samples : 0.000000053S


CLOCK_MONOTONIC_RAW ( using rdtscp() ) :

$ ./timer  -r 10
sum: 25755
Total time: 0.000025755S - Average Latency: 0.000000025S N zero
deltas: 0 N inconsistent deltas: 0
sum: 21614
Total time: 0.000021614S - Average Latency: 0.000000021S N zero
deltas: 0 N inconsistent deltas: 0
sum: 21616
Total time: 0.000021616S - Average Latency: 0.000000021S N zero
deltas: 0 N inconsistent deltas: 0
sum: 21610
Total time: 0.000021610S - Average Latency: 0.000000021S N zero
deltas: 0 N inconsistent deltas: 0
sum: 21619
Total time: 0.000021619S - Average Latency: 0.000000021S N zero
deltas: 0 N inconsistent deltas: 0
sum: 21617
Total time: 0.000021617S - Average Latency: 0.000000021S N zero
deltas: 0 N inconsistent deltas: 0
sum: 21610
Total time: 0.000021610S - Average Latency: 0.000000021S N zero
deltas: 0 N inconsistent deltas: 0
sum: 16940
Total time: 0.000016940S - Average Latency: 0.000000016S N zero
deltas: 0 N inconsistent deltas: 0
sum: 16939
Total time: 0.000016939S - Average Latency: 0.000000016S N zero
deltas: 0 N inconsistent deltas: 0
sum: 16943
Total time: 0.000016943S - Average Latency: 0.000000016S N zero
deltas: 0 N inconsistent deltas: 0
Average of 10 average latencies of 1000 samples : 0.000000019S

View attachment "timer_latency.c" of type "text/x-csrc" (3598 bytes)