On Fri, 2007-09-28 at 11:49 -0700, Andrew Morton wrote: > On Fri, 28 Sep 2007 13:00:53 -0400 Trond Myklebust <[EMAIL PROTECTED]> wrote: > > Do these patches also cause the memory reclaimers to steer clear of > > devices that are congested (and stop waiting on a congested device if > > they see that it remains congested for a long period of time)? Most of > > the collateral blocking I see tends to happen in memory allocation... > > > > No, they don't attempt to do that, but I suspect they put in place > infrastructure which could be used to improve direct-reclaimer latency. In > the throttle_vm_writeout() path, at least. > > Do you know where the stalls are occurring? throttle_vm_writeout(), or via > direct calls to congestion_wait() from page_alloc.c and vmscan.c? (running > sysrq-w five or ten times will probably be enough to determine this)
Looking back, they were getting caught up in balance_dirty_pages_ratelimited() and friends. See the attached example... Cheers Trond
--- Begin Message ---Hi, I am testing NFS on loopback locks up entire system with 2.6.23-rc6 kernel. I have mounted a local ext3 partition using loopback NFS (version 3) and started my test program. The test program forks 20 threads allocates 10MB for each thread, writes & reads a file on the loopback NFS mount. After running for about 5 min, I cannot even login to the machine. Commands like ps etc, hang in a live session. The machine is a DELL 1950 with 4Gig of RAM, so there is plenty of RAM & CPU to play around and no other io/heavy processes are running on the system. vmstat output shows no buffers are actually getting transferred in or out and iowait is 100%. [EMAIL PROTECTED] ~]# vmstat 1 procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------ r b swpd free buff cache si so bi bo in cs us sy id wa st 0 24 116 110080 11132 3045664 0 0 0 0 28 345 0 1 0 99 0 0 24 116 110080 11132 3045664 0 0 0 0 5 329 0 0 0 100 0 0 24 116 110080 11132 3045664 0 0 0 0 26 336 0 0 0 100 0 0 24 116 110080 11132 3045664 0 0 0 0 8 335 0 0 0 100 0 0 24 116 110080 11132 3045664 0 0 0 0 26 352 0 0 0 100 0 0 24 116 110080 11132 3045664 0 0 0 0 8 351 0 0 0 100 0 0 24 116 110080 11132 3045664 0 0 0 0 23 358 0 1 0 99 0 0 24 116 110080 11132 3045664 0 0 0 0 10 350 0 0 0 100 0 0 24 116 110080 11132 3045664 0 0 0 0 26 363 0 0 0 100 0 0 24 116 110080 11132 3045664 0 0 0 0 8 346 0 1 0 99 0 0 24 116 110080 11132 3045664 0 0 0 0 26 360 0 0 0 100 0 0 24 116 110080 11140 3045656 0 0 8 0 11 345 0 0 0 100 0 0 24 116 110080 11140 3045664 0 0 0 0 27 355 0 0 2 97 0 0 24 116 110080 11140 3045664 0 0 0 0 9 330 0 0 0 100 0 0 24 116 110080 11140 3045664 0 0 0 0 26 358 0 0 0 100 0 The following is the backtrace of 1. one of the threads of my test program 2. nfsd daemon and 3. a generic command like pstree, after the machine hangs: ------------------------------------------------------------- crash> bt 3252 PID: 3252 TASK: f6f3c610 CPU: 0 COMMAND: "test" #0 [f6bdcc10] schedule at c0624a34 #1 [f6bdcc84] schedule_timeout at c06250ee #2 [f6bdccc8] io_schedule_timeout at c0624c15 #3 [f6bdccdc] congestion_wait at c045eb7d #4 [f6bdcd00] balance_dirty_pages_ratelimited_nr at c045ab91 #5 [f6bdcd54] generic_file_buffered_write at c0457148 #6 [f6bdcde8] __generic_file_aio_write_nolock at c04576e5 #7 [f6bdce40] try_to_wake_up at c042342b #8 [f6bdce5c] generic_file_aio_write at c0457799 #9 [f6bdce8c] nfs_file_write at f8c25cee #10 [f6bdced0] do_sync_write at c0472e27 #11 [f6bdcf7c] vfs_write at c0473689 #12 [f6bdcf98] sys_write at c0473c95 #13 [f6bdcfb4] sysenter_entry at c0404ddf EAX: 00000004 EBX: 00000013 ECX: a4966008 EDX: 00980000 DS: 007b ESI: 00980000 ES: 007b EDI: a4966008 SS: 007b ESP: a5ae6ec0 EBP: a5ae6ef0 CS: 0073 EIP: b7eed410 ERR: 00000004 EFLAGS: 00000246 crash> bt 3188 PID: 3188 TASK: f74c4000 CPU: 1 COMMAND: "nfsd" #0 [f6836c7c] schedule at c0624a34 #1 [f6836cf0] __mutex_lock_slowpath at c062543d #2 [f6836d0c] mutex_lock at c0625326 #3 [f6836d18] generic_file_aio_write at c0457784 #4 [f6836d48] ext3_file_write at f8888fd7 #5 [f6836d64] do_sync_readv_writev at c0472d1f #6 [f6836e08] do_readv_writev at c0473486 #7 [f6836e6c] vfs_writev at c047358e #8 [f6836e7c] nfsd_vfs_write at f8e7f8d7 #9 [f6836ee0] nfsd_write at f8e80139 #10 [f6836f10] nfsd3_proc_write at f8e86afd #11 [f6836f44] nfsd_dispatch at f8e7c20c #12 [f6836f6c] svc_process at f89c18e0 #13 [f6836fbc] nfsd at f8e7c794 #14 [f6836fe4] kernel_thread_helper at c0405a35 crash> ps|grep ps 234 2 3 cb194000 IN 0.0 0 0 [khpsbpkt] 520 2 0 f7e18c20 IN 0.0 0 0 [kpsmoused] 2859 1 2 f7f3cc20 IN 0.1 9600 2040 cupsd 3340 3310 0 f4a0f840 UN 0.0 4360 816 pstree 3343 3284 2 f4a0f230 UN 0.0 4212 944 ps crash> bt 3340 PID: 3340 TASK: f4a0f840 CPU: 0 COMMAND: "pstree" #0 [e856be30] schedule at c0624a34 #1 [e856bea4] rwsem_down_failed_common at c04df6c0 #2 [e856bec4] rwsem_down_read_failed at c0625c2a #3 [e856bedc] call_rwsem_down_read_failed at c0625c96 #4 [e856bee8] down_read at c043c21a #5 [e856bef0] access_process_vm at c0462039 #6 [e856bf38] proc_pid_cmdline at c04a1bbb #7 [e856bf58] proc_info_read at c04a2f41 #8 [e856bf7c] vfs_read at c04737db #9 [e856bf98] sys_read at c0473c2e #10 [e856bfb4] sysenter_entry at c0404ddf EAX: 00000003 EBX: 00000005 ECX: 0804dc58 EDX: 00000062 DS: 007b ESI: 00000cba ES: 007b EDI: 0804e0e0 SS: 007b ESP: bfa3afe8 EBP: bfa3d4f8 CS: 0073 EIP: b7f64410 ERR: 00000003 EFLAGS: 00000246 ---------------------------------------------------------- Any ideas what could potentially trigger this? Please let me know if you would like to get any other specific details. Thanks --Chakri ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ NFS maillist - [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/nfs
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