性能測(cè)試分析之CPU篇

性能測(cè)試分析之CPU篇,目錄,Linux系統(tǒng)結(jié)構(gòu)簡(jiǎn)介用戶(hù)態(tài)CPU消耗分析內(nèi)核態(tài)CPU消耗分析硬中斷&軟中斷Loadaverage剖析,Linux系統(tǒng)結(jié)構(gòu),Linux系統(tǒng)結(jié)構(gòu),幾種CPU消耗,CPU調(diào)度,用戶(hù)態(tài)CPU,例1：程序cpuusr%瓶頸問(wèn)題定位。模擬程序TestMap主線程：死循環(huán)阻塞線程1：sleep線程2:循環(huán)mapfind操作,執(zhí)行命令：topHp7152,用戶(hù)態(tài)CPU,執(zhí)行命令：pstack7152,分析過(guò)程：通過(guò)topHpXX發(fā)現(xiàn)線程7153占用cpu特別高通過(guò)pstack發(fā)現(xiàn)線程7153在做map查詢(xún)操作，大量的紅黑樹(shù)查找操作。,用戶(hù)態(tài)CPU,例2：程序cpuusr%瓶頸問(wèn)題定位。（如果線程cpu消耗比較均衡）執(zhí)行：perftop-p7152-ecycles:u,參考案例：VTDU因CPU消耗過(guò)高回滾,內(nèi)核態(tài)CPU,例3：定位sy%消耗過(guò)高問(wèn)題執(zhí)行：perftop-pxxxx-ecycles:k,內(nèi)核態(tài)CPU,上下文切換（只會(huì)發(fā)生在內(nèi)核態(tài)）當(dāng)前執(zhí)行任務(wù)時(shí)間片用完，cpu正常調(diào)度下一個(gè)任務(wù)。I/O阻塞搶占鎖資源，用戶(hù)代碼掛起（sleep）,等待條件變量硬中斷&軟中斷,例4：程序問(wèn)題造成大量的上下文切換執(zhí)行：TestCsw程序開(kāi)啟100個(gè)線程，每個(gè)線程usleep（1*1000）,硬中斷&軟中斷,網(wǎng)卡中斷為例：頻繁的數(shù)據(jù)包收發(fā)會(huì)耗盡cpu時(shí)間,多核cpu，如何做中斷負(fù)載均衡？多隊(duì)列網(wǎng)卡：只需配置每個(gè)隊(duì)列的cpu親和性，smp_affinity。單隊(duì)列網(wǎng)卡：先通過(guò)RPS模擬出多隊(duì)列再最cpu親和性。RPS：根據(jù)數(shù)據(jù)包源地址、目的地址和源端口做hash，來(lái)選擇不同cpu。RFS：RPS負(fù)載均衡的優(yōu)化。,Loadaverage剖析,loadaverageSystemloadaveragesistheaveragenumberofprocessesthatareeitherinarunableoruninterruptablestate.AprocessinarunnablestateiseitherusingtheCPUorwaitingtousetheCPU.AprocessinuninterruptablestateiswaitingforsomeI/Oaccess,egwaitingfordisk.Theaveragesaretakenoverthethreetimeintervals.LoadaveragesarenotnormalizedforthenumberofCPUsinasystem,soaloadaverageof1meansasingleCPUsystemisloadedallthetimewhileona4CPUsystemitmeansitwasidle75%ofthetime.,進(jìn)程狀態(tài),Loadaverage剖析,例5：TASK_UNINTERRUPTIBLE狀態(tài)進(jìn)程過(guò)多導(dǎo)致load飆高執(zhí)行：LoadTest程序調(diào)用vfork（），父進(jìn)程進(jìn)入D