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Date: Fri, 29 Mar 2013 20:00:44 -0700 From: Tejun Heo <tj@...nel.org> To: axboe@...nel.dk, akpm@...ux-foundation.org Cc: jack@...e.cz, david@...morbit.com, linux-kernel@...r.kernel.org Subject: [PATCHSET] workqueue, writeback: better worker information in task dumps Hello, One of the problems that arise when converting dedicated custom threadpool to workqueue is that the shared worker pool used by workqueue anonimizes each worker making it more difficult to identify what the worker was doing on which target from the output of sysrq-t or debug dump from oops, BUG() and friends. For example, after writeback is converted to use workqueue instead of priviate thread pool, there's no easy to tell which backing device a writeback work item was working on at the time of task dump, which, according to our writeback brethren, is important in tracking down issues with a lot of mounted file systems on a lot of different devices. This patchset implements a way for a work function to mark its execution instance so that task dump of the worker task includes information to indicate what the work item was doing. An example WARN dump would look like the following. WARNING: at /work/os/work/fs/fs-writeback.c:1015 bdi_writeback_workfn+0x2b4/0x3c0() Modules linked in: Pid: 28, comm: kworker/u18:0 Not tainted 3.9.0-rc1-work+ #24 empty empty/S3992 Workqueue: writeback bdi_writeback_workfn (flush-8:16) ffffffff820a3a98 ffff88015b927cb8 ffffffff81c61855 ffff88015b927cf8 ffffffff8108f500 0000000000000000 ffff88007a171948 ffff88007a1716b0 ffff88015b49df00 ffff88015b8d3940 0000000000000000 ffff88015b927d08 Call Trace: [<ffffffff81c61855>] dump_stack+0x19/0x1b [<ffffffff8108f500>] warn_slowpath_common+0x70/0xa0 ... This patchset contains the following three patches. 0001-kthread-implement-probe_kthread_data.patch 0002-workqueue-include-workqueue-info-when-printing-debug.patch 0003-writeback-set-worker-desc-to-identify-writeback-work.patch 0001 adds a speculative accessor for kthread_data. 0002 implements worker description. 0003 updates writeback to set its flusher name as worker description. This patchset is on top of [1] workqueue: NUMA affinity for unbound workqueues + [2] writeback: convert writeback to unbound workqueue + [3] arch: unify task dump debug info and available in the following git branch. git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git review-better-dbg Due to the dependencies, routing this set would be a bit complicated. I think it would be best to first pull wq/for-3.10 to block tree and apply workqueue conversion patchset. The patches in this series then can go through -mm on top of all three pieces - workqueue, block and archs. diffstat follows. Thanks. fs/fs-writeback.c | 1 include/linux/kthread.h | 1 include/linux/workqueue.h | 5 ++ kernel/kthread.c | 19 ++++++++++ kernel/sched/core.c | 1 kernel/workqueue.c | 79 ++++++++++++++++++++++++++++++++++++++++++++ kernel/workqueue_internal.h | 12 ++++++ lib/dump_stack.c | 2 + 8 files changed, 119 insertions(+), 1 deletion(-) -- tejun [1] http://thread.gmane.org/gmane.linux.kernel/1465626 [2] http://thread.gmane.org/gmane.linux.kernel/1453006 [3] https://lkml.org/lkml/2013/3/29/354 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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