Instead of using sync, could you increase the size of the files you write so that they are 10x ram size?
I have a suspicion we are slow at sync.... I am not sure why, but I have seen other data where sync was slow for us, and maybe we need to optimize that code path. Hans Laurent Riffard wrote: >Le 22.03.2006 08:41, Hans Reiser a écrit : > > >>Laurent Riffard wrote: >> >> >> >> >>>Hello, >>> >>>Writing big files is very slow on reiser4 now. >>> >>>"dd if=/dev/zero of=toto bs=1k count=102400; sync" >>> >>> >>> >>try bs=4M, and tell me what happens. also try an empty fs, and an fs >>that is equally full to reiserfs. Note that reiserfs in your test is >>68% full vs. 90% full for V4. It may be that we need to port some of >>the block allocation optimizations from V3 to V4 (Jeff's work) to help >>with 90% full filesystems. Thanks for doing this. Real users always >>teach me a lot when they test things differently from how I did. >> >>Hans >> >> > >Hello Hans, > >Yesterday, I realized that my tests were not fair. So I did some >further tests trying to have the same situation for 3 different FS >(reiserfs/ext2/reiser4) and I sent the result to the list, but this >mail never reached the list. I have resent it. > >As per your request, I tried to replay my dd test on my 90% full >reiser4 FS, using a 4M block size. Here are the results: > >--------------------- > > >>Desktop$ cd ~/kernel >> >>kernel$ rm toto >>rm: détruire fichier régulier `toto'? o >> >>kernel$ df . >>Sys. de fich. Tail. Occ. Disp. %Occ. Monté sur >>/dev/hda8 925M 748M 177M 81% /home/laurent/kernel >> >>kernel$ grep /dev/hda8 /rpoc/mounts >>grep: /rpoc/mounts: Aucun fichier ou répertoire de ce type >> >>kernel$ grep /dev/hda8 /proc/mounts >>/dev/hda8 /home/laurent/kernel reiser4 >>rw,nosuid,nodev,atom_max_size=0x7e0c,atom_max_age=0x249f0,atom_min_size=0x100,atom_max_flushers=0x1,cbk_cache_slots=0x10 >> 0 0 >> >>kernel$ sync; time dd if=/dev/zero of=toto bs=4M count=25; time sync >>25+0 enregistrements lus. >>25+0 enregistrements écrits. >>0.00user 2.89system 0:17.18elapsed 16%CPU (0avgtext+0avgdata 0maxresident)k >>0inputs+0outputs (0major+252minor)pagefaults 0swaps >>0.00user 0.00system 2:19.91elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k >>0inputs+0outputs (0major+191minor)pagefaults 0swaps >> >>kernel$ sync; time dd if=/dev/zero of=toto bs=4M count=25; time sync >>25+0 enregistrements lus. >>25+0 enregistrements écrits. >>0.00user 2.96system 1:16.42elapsed 3%CPU (0avgtext+0avgdata 0maxresident)k >>0inputs+0outputs (0major+252minor)pagefaults 0swaps >>0.00user 0.00system 0:08.70elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k >>0inputs+0outputs (0major+190minor)pagefaults 0swaps >> >> >--------------------- > >I tried to run an "iostat 10" simultaneously with dd+sync. I >attached the output. Hope this helps. >~~ >laurent > > >------------------------------------------------------------------------ > >Le script a débuté sur mer 22 mar 2006 19:12:56 CET >Desktop$ cd ~/kernel >kernel$ >kernel$ sleep 15 && echo SYNC && sync && echo DD && time dd if=/dev/zero >of=toto bs=4M count=25 && echo SYNC && time sync && echo END & >[1] 4657 >kernel$ iostat -t 10 /dev/hda8 >Linux 2.6.16-rc6-mm2 (antares.localdomain) 22.03.2006 > >Heure: 19:13:32 >avg-cpu: %user %nice %system %iowait %idle > 5,01 0,02 11,07 4,45 79,46 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 5,34 0,27 217,58 1297 1026592 > >Heure: 19:13:42 >avg-cpu: %user %nice %system %iowait %idle > 0,10 0,00 0,20 0,20 99,50 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 0,00 0,00 0,00 0 0 > >SYNC >DD >Heure: 19:13:52 >avg-cpu: %user %nice %system %iowait %idle > 1,50 0,00 79,32 8,29 10,89 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 20,38 3,20 1202,00 32 12032 > >Heure: 19:14:02 >avg-cpu: %user %nice %system %iowait %idle > 2,30 0,00 81,08 16,62 0,00 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 33,53 0,00 1398,20 0 13968 > >Heure: 19:14:12 >avg-cpu: %user %nice %system %iowait %idle > 1,90 0,00 88,51 9,59 0,00 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 25,27 0,00 893,51 0 8944 > >Heure: 19:14:22 >avg-cpu: %user %nice %system %iowait %idle > 3,19 0,00 85,63 11,18 0,00 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 27,35 0,00 1288,62 0 12912 > >Heure: 19:14:32 >avg-cpu: %user %nice %system %iowait %idle > 0,80 0,00 90,01 9,19 0,00 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 25,17 0,00 800,00 0 8008 > >Heure: 19:14:42 >avg-cpu: %user %nice %system %iowait %idle > 0,30 0,00 74,93 24,78 0,00 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 54,35 0,00 3138,46 0 31416 > >Heure: 19:14:52 >avg-cpu: %user %nice %system %iowait %idle > 0,20 0,00 81,62 18,18 0,00 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 50,75 0,00 1324,28 0 13256 > >Heure: 19:15:02 >avg-cpu: %user %nice %system %iowait %idle > 0,60 0,00 71,60 27,80 0,00 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 76,30 0,00 2363,20 0 23632 > >Heure: 19:15:12 >avg-cpu: %user %nice %system %iowait %idle > 1,10 0,00 29,77 68,93 0,20 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 123,78 0,00 3275,12 0 32784 > >25+0 enregistrements lus. >25+0 enregistrements écrits. >0.00user 2.94system 1:29.83elapsed 3%CPU (0avgtext+0avgdata 0maxresident)k >0inputs+0outputs (0major+252minor)pagefaults 0swaps >SYNC >Heure: 19:15:22 >avg-cpu: %user %nice %system %iowait %idle > 2,90 0,00 76,60 19,10 1,40 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 55,10 0,80 1435,20 8 14352 > >0.00user 0.00system 0:17.41elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k >0inputs+0outputs (0major+190minor)pagefaults 0swaps >END >Heure: 19:15:32 >avg-cpu: %user %nice %system %iowait %idle > 0,10 0,00 31,73 42,14 26,03 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 94,19 0,00 3402,60 0 33992 > >Heure: 19:15:42 >avg-cpu: %user %nice %system %iowait %idle > 0,10 0,00 0,00 0,10 99,80 > >Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn >hda8 0,00 0,00 0,00 0 0 > > >^C >[1]+ Done sleep 15 && echo SYNC && sync && echo DD && time >dd if=/dev/zero of=toto bs=4M count=25 && echo SYNC && time sync && echo END >kernel$ exit > >Script complété sur mer 22 mar 2006 19:15:46 CET > >
