On Sat, May 07, 2005 at 09:10:17PM -0400, Dan Malek wrote: > > On May 6, 2005, at 11:45 AM, Marcelo Tosatti wrote: > > > > >Hi Dan, > > > >So, restarting this conversation... > > One of the things I don't want to lose sight of during > all of this is the real performance problem in 2.6. > Your test results show there is something that needs > attention, regardless of using pinned entries. We > need to continue some of this investigation, it > affects all processors.
True. Follows some useful data: "itlb-content-before" and "itlb-content-after" are dumps of TLB cache content before and after "sys_read()", for both v2.4 and v2.6. The "diff" output shows which TLB's have been faulted in: [marcelo at logos itlb]$ diff -u 24-itlb-content-before.txt 24-itlb-content-after.txt | grep SPR | grep 816 | grep "+" +SPR 816 : 0x0ffe800f 268337167 +SPR 816 : 0x0ffeb00f 268349455 +SPR 816 : 0xc009e01f -1073094625 +SPR 816 : 0xc009d01f -1073098721 +SPR 816 : 0xc000301f -1073729505 +SPR 816 : 0xc009c01f -1073102817 [marcelo at logos itlb]$ diff -u 24-itlb-content-before.txt 24-itlb-content-after.txt | grep SPR | grep 818 | grep "+" | wc -l 6 Now v2.6: [marcelo at logos itlb]$ diff -u 26-itlb-before.txt 26-itlb-after.txt | grep 816 | grep SPR | grep "+" +SPR 816 : 0x0feda16f 267231599 +SPR 816 : 0xc004b17f -1073434241 +SPR 816 : 0xc004a17f -1073438337 +SPR 816 : 0x0ff7e16f 267903343 +SPR 816 : 0x1001016f 268501359 +SPR 816 : 0xc000217f -1073733249 +SPR 816 : 0xc001617f -1073651329 +SPR 816 : 0xc002e17f -1073553025 +SPR 816 : 0xc010e17f -1072635521 +SPR 816 : 0xc002d17f -1073557121 +SPR 816 : 0xc010d17f -1072639617 +SPR 816 : 0xc000c17f -1073692289 +SPR 816 : 0xc000317f -1073729153 [marcelo at logos itlb]$ diff -u 26-itlb-before.txt 26-itlb-after.txt | grep 816 | grep SPR | grep "+" | wc -l 13 So, for sys_read() v2.6 i-cache translation footprint is about 100% more than v2.4. I suspect that actual cache footprint is higher, too.
