On Tue, 19 Oct 2010 14:23:29 +0900 Minchan Kim <minchan.kim@xxxxxxxxx> wrote: > On Tue, Oct 19, 2010 at 11:59 AM, KAMEZAWA Hiroyuki > <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > > On Tue, 19 Oct 2010 10:07:38 +0800 > > "Figo.zhang" <zhangtianfei@xxxxxxxxxxxxxxxx> wrote: > > > >> > >> > > >> > very lots of change ;) > >> > can you please send us your crash log? > >> > >> i add some prink in select_bad_process() and oom_badness() to see > >> pid/totalpages/points/memoryuseage/and finally process to selet to kill. > >> > >> i found it the oom-killer select: syslog-ng,mysqld,nautilus,VirtualBox > >> to kill, so my question is: > >> > >> 1. the syslog-ng,mysqld,nautilus is the system foundamental process, so > >> if oom-killer kill those process, the system will be damaged, such as > >> lose some important data. > >> > >> 2. the new oom-killer just use percentage of used memory as score to > >> select the candidate to kill, but how to know this process to very > >> important for system? > >> > > > > The kernel can never know it. Just an admin (a man or management software) knows. > > Old kernel tries to guess it, but it tend to be wrong and many many report comes > > "why my ....is killed..." All guesswork the kernel does is not enough, I think. > > > >> oom_score_adj, it is anyone commercial linux distributions to use this > >> to protect the critical process. > >> > > oom_adj may be used in some system. All my customers select panic_at_oom=1 > > and cause cluster fail over rather than half-broken. > > > > <Off topic> > > Your another choice is memory cgroup, I think. > > please see documentation/cgroup/memory.txt or libcgroup. > > http://sourceforge.net/projects/libcg/ > > You can use some fancy controls with it. > > </Off topic> > > > > > > BTW, there seems to be some strange things. > > (CC'ed to linux-mm) > > Brief Summary: > > Â an oom-killer happens on swapless environment with 2.6.36-rc8. > > Â It has 2G memory. > > a reporter says > > == > >> i want to test the oom-killer. My desktop (Dell optiplex 780, i686 > >> kernel)have 2GB ram, i turn off the swap partition, and open a huge pdf > >> files and applications, and let the system eat huge ram. > >> > >> in 2.6.35, i can use ram up to 1.75GB, > >> > >> but in 2.6.36-rc8, i just use to 1.53GB ram , the system come very slow > >> and crashed after some minutes , the DiskIO is very busy. i see the > >> DiskIO read is up to 8MB/s, write just only 400KB/s, (see by conky). > > == > > > > The trigger of oom-kill is order=0 allocation. (see original mail for full log) > > > > > > Oct 19 09:44:08 myhost kernel: [ Â618.441470] httpd invoked oom-killer: > > gfp_mask=0x201da, order=0, oom_adj=0, oom_score_adj=0 > > > > Zone's stat is. > > > > Oct 19 09:44:08 myhost kernel: [ Â618.441551] > > DMA free:7968kB min:64kB low:80kB high:96kB active_anon:3700kB inactive_anon:3752kB > > Â Âactive_file:12kB inactive_file:252kB unevictable:0kB isolated(anon):0kB > > Â Âisolated(file):0kB present:15788kB mlocked:0kB dirty:0kB writeback:4kB > > Â Âmapped:52kB shmem:348kB slab_reclaimable:0kB slab_unreclaimable:16kB > > Â Âkernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB > > Â Âwriteback_tmp:0kB pages_scanned:421 all_unreclaimable? yes > > Â Âlowmem_reserve[]: 0 865 1980 1980 > > > > Oct 19 09:44:08 myhost kernel: [ Â618.441560] > > Normal free:39348kB min:3728kB low:4660kB high:5592kB active_anon:176740kB > > Â Â Â inactive_anon:25640kB active_file:84kB inactive_file:308kB > > Â Â Â unevictable:0kB isolated(anon):0kB isolated(file):0kB present:885944kB > > Â Â Â mlocked:0kB dirty:0kB writeback:4kB mapped:576992kB shmem:5024kB > > Â Â Â slab_reclaimable:7612kB slab_unreclaimable:15512kB kernel_stack:2792kB > > Â Â Â pagetables:6884kB unstable:0kB bounce:0kB writeback_tmp:0kB > > Â Â Â pages_scanned:741 all_unreclaimable? yes > > Â Â Â lowmem_reserve[]: 0 0 8921 8921 > > > > Oct 19 09:44:08 myhost kernel: [ Â618.441569] > > HighMem free:392kB min:512kB low:1712kB high:2912kB active_anon:492208kB > > Â Â Â Âinactive_anon:166404kB active_file:180kB inactive_file:840kB > > Â Â Â Âunevictable:40kB isolated(anon):0kB isolated(file):0kB present:1141984kB > > Â Â Â Âmlocked:40kB dirty:0kB writeback:12kB mapped:493648kB shmem:72216kB > > Â Â Â Âslab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB > > Â Â Â Âpagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB > > Â Â Â Âpages_scanned:1552 all_unreclaimable? yes > > > > Highmem seems a bit strange. > > Âpresent(1141984) - active_anon - inactive_anon - inactive_file - active_file > > Â= 482352kB but free is 392kB. > > > > ÂHighmem is used for some other purpose than usual user's page.(pagetable is 0.) > > ÂAnd, Hmm, mapped:493648kB seems too large for me. > > Â(active/inactive-file + shmem is not enough.) > > ÂAnd "mapped" in NORMAL zone is large, too. > > > > ÂDoes anyone have idea about file-mapped-but-not-on-LRU pages ? > > Isn't it possible some file pages are much sharable? > Please see the page_add_file_rmap. > page_add_file_rmap() just counts an event where mapcount goes 0->1. Even if thousands process shares a page, it's just counted into file_mapped as 1. Then, there are 480MB of mapped file caches. Do I miss something ? Anyway, sum-of-all-lru-of-highmem is 480MB smaller than present pages. and isolated(anon/file) is 0kB. (NORMAL has similar problem) Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>