Date: Tue, 28 Feb 2017 19:46:21 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-virtualization@FreeBSD.org Subject: [Bug 216759] [kern] Memory speed with small blocks (1K) up to 35 times slower than host system (under QEMU emulation, but not only) Message-ID: <bug-216759-27103-LXk0hjK8Rt@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-216759-27103@https.bugs.freebsd.org/bugzilla/> References: <bug-216759-27103@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D216759 --- Comment #11 from andrew@azar-a.net --- Here are the latest results supporting my previous post: root@debian8-test:~# sysbench --num-threads=3D1 --test=3Dmemory --memory-total-size=3D512M --memory-block-size=3D1K --debug run sysbench 0.4.12: multi-threaded system evaluation benchmark Running the test with following options: Number of threads: 1 Debug mode enabled. Doing memory operations speed test Memory block size: 1K Memory transfer size: 512M Memory operations type: write Memory scope type: global Threads started! DEBUG: Runner thread started (0)! Done. Operations performed: 524288 (3877252.90 ops/sec) 512.00 MB transferred (3786.38 MB/sec) Test execution summary: total time: 0.1352s total number of events: 524288 total time taken by event execution: 0.1093 per-request statistics: min: 0.00ms avg: 0.00ms max: 0.14ms approx. 95 percentile: 0.00ms Threads fairness: events (avg/stddev): 524288.0000/0.00 execution time (avg/stddev): 0.1093/0.00 DEBUG: Verbose per-thread statistics: DEBUG: thread # 0: min: 0.0000s avg: 0.0000s max: 0.0001s events: 524288 DEBUG: total time taken by even execution: 0.1093s root@debian8-test:~# cat /sys/bus/clocksource/devices/clocksource0/current_clocksource tsc root@debian8-test:~# cat /sys/bus/clocksource/devices/clocksource0/available_clocksource tsc hpet acpi_pm root@dev:~ # dmesg | grep -i "TSC" Calibrating TSC clock ... TSC clock: 3400129027 Hz =20 Features=3D0xf83fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,M= CA,CMOV,PAT,PSE36,MMX,FXSR,SSE,SSE2,SS> =20 Features2=3D0xfffa3203<SSE3,PCLMULQDQ,SSSE3,FMA,CX16,PCID,SSE4.1,SSE4.2,x2A= PIC,MOVBE,POPCNT,TSCDLT,AESNI,XSAVE,OSXSAVE,AVX,F16C,RDRAND,HV> AMD Features=3D0x2c100800<SYSCALL,NX,Page1GB,RDTSCP,LM> TSC timecounter discards lower 1 bit(s) Timecounter "TSC-low" frequency 1700064513 Hz quality -100 root@dev:~ # sysbench --num-threads=3D1 --test=3Dmemory --memory-total-size= =3D512M --memory-block-size=3D1K --debug run sysbench 0.4.12: multi-threaded system evaluation benchmark Running the test with following options: Number of threads: 1 Debug mode enabled. Doing memory operations speed test Memory block size: 1K Memory transfer size: 512M Memory operations type: write Memory scope type: global Threads started! DEBUG: Runner thread started (0)! Done. Operations performed: 524288 (73267.52 ops/sec) 512.00 MB transferred (71.55 MB/sec) Test execution summary: total time: 7.1558s total number of events: 524288 total time taken by event execution: 5.2780 per-request statistics: min: 0.01ms avg: 0.01ms max: 0.72ms approx. 95 percentile: 0.00ms Threads fairness: events (avg/stddev): 524288.0000/0.00 execution time (avg/stddev): 5.2780/0.00 DEBUG: Verbose per-thread statistics: DEBUG: thread # 0: min: 0.0000s avg: 0.0000s max: 0.0007s events: 524288 DEBUG: total time taken by even execution: 5.2780s root@dev:~ # sysctl kern.timecounter.hardware=3DTSC-low kern.timecounter.hardware: HPET -> TSC-low root@dev:~ # sysbench --num-threads=3D1 --test=3Dmemory --memory-total-size= =3D512M --memory-block-size=3D1K --debug run sysbench 0.4.12: multi-threaded system evaluation benchmark Running the test with following options: Number of threads: 1 Debug mode enabled. Doing memory operations speed test Memory block size: 1K Memory transfer size: 512M Memory operations type: write Memory scope type: global Threads started! DEBUG: Runner thread started (0)! Done. Operations performed: 524288 (3408336.84 ops/sec) 512.00 MB transferred (3328.45 MB/sec) Test execution summary: total time: 0.1538s total number of events: 524288 total time taken by event execution: 0.1102 per-request statistics: min: 0.00ms avg: 0.00ms max: 0.24ms approx. 95 percentile: 0.00ms Threads fairness: events (avg/stddev): 524288.0000/0.00 execution time (avg/stddev): 0.1102/0.00 DEBUG: Verbose per-thread statistics: DEBUG: thread # 0: min: 0.0000s avg: 0.0000s max: 0.0002s events: 524288 DEBUG: total time taken by even execution: 0.1102s So it's even worse than memory lag - it's gettimeofday() function lag, basically all software relies on it one way or another.... --=20 You are receiving this mail because: You are the assignee for the bug.=
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