<div class="__aliyun_email_body_block"><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;">Hi,dev</div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><br data-mce-bogus="1"></div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;">    About a month ago,I asked a question about how to do time recording for ust event when vdso_clock_gettime not availble on my platform(Glibc too old).Recently I implemented a lib to analyze vdso in memory and lookuped the symbol vdso_clock_gettime successfully.With this vdso_clock_gettime availble,I get a 16% improvement in time spending per ust event. I.E. I measured the time taked by a event with 10 bytes string :</div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><br data-mce-bogus="1"></div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"> no   vdso_clock_gettime : 0.642us</div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"> with vdso_clock_gettime:0.554us</div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><br data-mce-bogus="1"></div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;">However,Both the numbers are much higher than the following 0.28us(But closed to 0.5us --W/O opt). So what's the difference between UST(0.28us) and UST W/O OPT(0.5us)?? </div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><br data-mce-bogus="1"></div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><img src="cid:__aliyun143010367216577271" alt="" class="__aliyun_inline_attach_1"></div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><br data-mce-bogus="1"></div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><br data-mce-bogus="1"></div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;">PS:My hardware</div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;">2 x Xeon E5-2430  2.20GHz 100MHz FSB (24 cores) 94.6GB / 96GB 1333MHz DDR3 == 6 x 16GB, 6 x empty</div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><br data-mce-bogus="1"></div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;">Thanks</div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;">zhenyu.ren</div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><br></div><div class="__aliyun_signature_wrap"></div><div style="font-family:Tahoma,Arial,STHeiti,SimSun;font-size:14px;color:#000000;"><br></div></div>