I. Peter Wong - rmap performance testing rmap consumes a lot of memory and many pte's. using read (as compared to readv) without rmap on 2.5.25 was the only way he was able to finish the runs. martin said he is running into memory issues and they know the problem and will have the fixes soon. Martin told him to try using threads instead of processes or less tasks in general that might help peters runs. there are optimizations in 2.5.37 that will make rmap take up almost half the space. Badari asked if he was not able to get any throughput runs yet (even without rmap)? Peter said that is true. II. Duc Vianney - Hyperthreading performance He is using multithreaded benchmarks. Did not see a big difference between hyperthreading and no hyperthreading. except in aim 9 sync disk test there was a 38% degredation. unfortunately the hardware was taken away so he can not rerun that test right now. eventually he will get it back and should be able to test it again. Martin asked them to try to rerun the aim 9 test again since that is the only one showing interesting results and it should be fixed. III. Dave McCracken - rmap performance testing (rollup patch backported to 2.5.26) He wanted to enable testing of base rmap against nonrmap for performance testing. 2.5.26 was the release before rmap went in. took the original patch that got merged plus some of the basic optimizations against 2.5.26. performance team tested it and in general showed it was not a significant cost. some of the tests they ran didnt stress the areas where it (fork, exec) might have a cost. but akpm is testing fork and exec. However, when they started testing with volanomark (paging) it showed some performance hits. Martin said it wasnt what they were expecting since they thought the static overhead would be the most cost and would help most wiht paging. but that wasnt the case at least with this 2.5.26 (also with -mm1 was slower). so something is still broken there. Dave reminded everyone there are other changes in 2.5 besides rmap. Dave thinks we will just have to live with the instabilities and keep testing as changes come out and try to abstract out which parts are memory related and which ones are not. Badari reminded everyone that 2.5.32 and on is bouncing need akpms scsi_hack otherwise you bounce. It is a one line fix you will need otherwise you will bounce. but since it is a hack akpm is not pushing it to Linus. IV. Martin Bligh - rmap status Covered most already but we know there are performance issues. linus has merged the intel large page support patch. going to try to replace the interface to make it more standard and easier to use. all of it should be done before halloween. bill hartner asked where intel has the interface documented. laughter, regarding his optimism. it would be nice to see it documented though. bill hartner has a question about large memory reducing tlb misses. martin increase tlb coverage by a factor of a 1000. how measureable is the reduction in tlb misses? martin - mostly shown by faster processes and memory interfaces. mainly win in not stalling the cpu. bill was thinking about some performance counters to measure stalls. andi kleen was having horrendous tlb misses using gcc and something? V. Bill Hartner Rik asked for 2.4.19 measurements. baseline with O1 scheduler. noticed that even on 4bg system should not swap with 2.4 rmap patch. even with 1/2 gig free memory it is swapping. martin said to definitely mail that out. Bill going to rerun with 2bg swap. might not have those out until monday.