fio基础20

log_compression=intIfthisisset,fiowillcompresstheIOlogsasitgoes,tokeepthememoryfootprintlower.Whenalogreachesthespecifiedsize,thatchunkisremovedandcompressedinthebackground.GiventhatIOlogsarefairlyhighlycompressible,thisyieldsanicememorysavingsforlongerruns.ThedownsideisthatthecompressionwillconsumesomebackgroundCPUcycles,soitmayimpacttherun.This,however,isalsotrueiftheloggingendsupconsumingmostofthesystemmemory.Sopickyourpoison.TheIOlogsaresavednormallyattheendofarun,bydecompressingthechunksandstoringtheminthespecifiedlogfile.Thisfeaturedependsontheavailabilityofzlib.log_store_compressed=boolIfset,andlog_compressionisalsoset,fiowillstorethelogfilesinacompressedformat.Theycanbedecompressedwithfio,usingthe--inflate-logcommandlineparameter.Thefileswillbestoredwitha.fzsuffix.block_error_percentiles=boolIfset,recorderrorsintrimblock-sizedunitsfromwritesandtrimsandoutputahistogramofhowmanytrimsittooktogettoerrors,andwhatkindoferrorwasencountered.lockmem=intPindownthespecifiedamountofmemorywithmlock(2).Canpotentiallybeusedinsteadofremovingmemoryorbootingwithlessmemorytosimulateasmalleramountofmemory.Theamountspecifiedisperworker.exec_prerun=strBeforerunningthisjob,issuethecommandspecifiedthroughsystem(3).Outputisredirectedinafilecalledjobname.prerun.txt.exec_postrun=strAfterthejobcompletes,issuethecommandspecifiedthoughsystem(3).Outputisredirectedinafilecalledjobname.postrun.txt.ioscheduler=strAttempttoswitchthedevicehostingthefiletothespecifiedioschedulerbeforerunning.disk_util=boolGeneratediskutilizationstatistics,iftheplatformsupportsit.Defaultstoon.disable_lat=boolDisablemeasurementsoftotallatencynumbers.Usefulonlyforcuttingbackthenumberofcallstogettimeofday,asthatdoesimpactperformanceatreallyhighIOPSrates.Notethattoreallygetridofalargeamountofthesecalls,thisoptionmustbeusedwithdisable_slatanddisable_bwaswell.disable_clat=boolDisablemeasurementsofcompletionlatencynumbers.Seedisable_lat.disable_slat=boolDisablemeasurementsofsubmissionlatencynumbers.Seedisable_slat.disable_bw=boolDisablemeasurementsofthroughput/bandwidthnumbers.Seedisable_lat.clat_percentiles=boolEnablethereportingofpercentilesofcompletionlatencies.percentile_list=float_listOverwritethedefaultlistofpercentilesforcompletionlatenciesandtheblockerrorhistogram.Eachnumberisafloatingnumberintherange(0,100],andthemaximumlengthofthelistis20.Use':'toseparatethenumbers,andlistthenumbersinascendingorder.Forexample,--percentile_list=99.5:99.9willcausefiotoreportthevaluesofcompletionlatencybelowwhich99.5%and99.9%oftheobservedlatenciesfell,respectively.clocksource=strUsethegivenclocksourceasthebaseoftiming.Thesupportedoptionsare:gettimeofdaygettimeofday(2)clock_gettimeclock_gettime(2)cpuInternalCPUclocksourcecpuisthepreferredclocksourceifitisreliable,asitisveryfast(andfioisheavyontimecalls).Fiowillautomaticallyusethisclocksourceifit's supported and considered reliable on the system it is running on, unless another clocksource is specifically set. For x86/x86-64 CPUs, this means supporting TSC Invariant. gtod_reduce=bool Enable all of the gettimeofday() reducing options (disable_clat, disable_slat, disable_bw) plus reduce precision of the timeout somewhat to really shrink the gettimeofday() call count. With this option enabled, we only do about 0.4% of the gtod() calls we would have done if all time keeping was enabled. gtod_cpu=int Sometimes it'scheapertodedicateasinglethreadofexecutiontojustgettingthecurrenttime.Fio(anddatabases,forinstance)areveryintensiveongettimeofday()calls.Withthisoption,youcansetoneCPUasidefordoingnothingbutloggingcurrenttimetoasharedmemorylocation.Thentheotherthreads/processesthatrunIOworkloadsneedonlycopythatsegment,insteadofenteringthekernelwithagettimeofday()call.TheCPUsetasidefordoingthesetimecallswillbeexcludedfromotheruses.FiowillmanuallyclearitfromtheCPUmaskofotherjobs.continue_on_error=strNormallyfiowillexitthejobonthefirstobservedfailure.Ifthisoptionisset,fiowillcontinuethejobwhenthereisa'non-fatal error'(EIOorEILSEQ)untiltheruntimeisexceededortheI/Osizespecifiediscompleted.Ifthisoptionisused,therearetwomorestatsthatareappended,thetotalerrorcountandthefirsterror.Theerrorfieldgiveninthestatsisthefirsterrorthatwashitduringtherun.