I graphed pagefaults on firefox startup which showed that there some bonus page faults caused by the default section order. The main problem is backwards io which always causes page faults. For reference click the second rectange in http://people.mozilla.com/~tglek/startup/systemtap_graphs/visualize.html?#ld_bug/log.txt.html x-axis is file offset, y-axis is time
Log of the sections being read is in http://people.mozilla.com/~tglek/startup/systemtap_graphs/ld_bug/report.txt Fault #1: This likely can't fixed in ld, but mentioning it in case Going through the log chronologically there the problems are: .bss is being zeroed which causes copy-on-write io. Then .dynamic is being read. The fix should be in the dynamic linker to read .dynamic before memset. This would allow binaries(where distance between .dynamic and .bss is smaller than the kernel's readhead) to avoid the .bss pagefault. Perhaps .dynamic should be the last section before .bss? Alternatively ld could force .bss to point past the end of the file. Fault #2 .gnu.version* should be in front of .dyn(sym|str) Fault #3 .dynstr should be in front of .dynsym Would be nice if .eh_frame* could be in front of .fini, but as far as I can tell these have to be in different segments. -- Summary: default section layout should be improved to reduce pagefaults Product: binutils Version: unspecified Status: NEW Severity: normal Priority: P2 Component: ld AssignedTo: unassigned at sources dot redhat dot com ReportedBy: tglek at mozilla dot com CC: bug-binutils at gnu dot org http://sourceware.org/bugzilla/show_bug.cgi?id=11447 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is. _______________________________________________ bug-binutils mailing list bug-binutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-binutils
