linux调试和性能剖析手段（linux debug and profiling）

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1、LinuxDebuggingandProfilingBarrySong2014GCCgcc+glibc+linux-header+make!The"makeheaders_install"commandexportsthekernel'sheaderfilesinaformsuitableforusebyuserspaceprograms.!Kernelheadersarebackwardscompatible,butnotforwardscompatible.ThismeansthataprogrambuiltagainstaClibraryusin

2、golderkernelheadersshouldrunonanewerkernel(althoughitmaynothaveaccesstonewfeatures),butaprogrambuiltagainstnewerkernelheadersmaynotworkonanolderkernel.!EmbeddedGLIBC(EGLIBC)wasavariantoftheGNUCLibrary(GLIBC)thatwasdesignedtoworkwellonembeddedsystems.EGLIBCstrivedtobesourceandbin

3、arycompatiblewithGLIBC.EGLIBC'sgoalsincludedreducedfootprint,configurablecomponents,bettersupportforcross-compilationandcross-testing.GCCcompilationprocess!Preprocessing!Compilation!Assembly!Linking$lshelloworld.c$gcc-Wall-save-tempshelloworld.c-ohelloworld$lshelloworldhelloworl

4、d.chelloworld.ihelloworld.ohelloworld.sThetemporaryfilesproducedby-save-tempsflaginonegocanbeproducedonebyonebyusingthegccflags-E,-Cand-Sateachofthepreprocessing,compilationandassemblystepsrespectively.preprocessing!Thepreprocessingstep:alltheheaderfilesthatyouhaveincludedinyour

5、programareactuallyexpandedandincludedinsourcecodeofyourprogram.Otherthanthis,allthemacrosarereplacedbytheirrespectivevaluesalloverthecodeandallthecommentsarestrippedoff.!Thecompilationstep:thesourcecodeisactuallycompiledbythecompilertoproduceanassemblycode.Assemblycodeconsistofs

6、etofinstructionsthatdeterminewhatyouprogramwantstodo.!Theassemblystep:theassemblerunderstandstheassemblyinstructionsandconvertseachofthemintothecorrespondingmachinelevelcodeorabitstreamthatconsistsof0’sand1’s.Thismachinelevelcodeisknownasobjectcodeandthiscodecanbeexecutedbythepr

7、ocessor.!Thelinkingstep:Oncetheobjectfilecontainingthemachinecodeisproducedinthestepabove,thelinkingstepmakessurethatalltheundefinedsymbolsincodeareresolved.Options:-O,-O1,-O2,-O3,-O0,-Os"Variouslevelsofoptimizationofthecode"-O1to-O3arevariousdegreesofoptimizationtargetedforspee

8、d"If-Oisadded,thenthecodesizeisconsidered"-O0me