Messages in this thread |  | | | Date | Sun, 6 Sep 2009 20:43:59 +0200 | | From | Jens Axboe <> | | Subject | Re: [PATCH 2/8] writeback: move dirty inodes from super_block to backing_dev_info |
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On Fri, Sep 04 2009, Christoph Hellwig wrote: > On Fri, Sep 04, 2009 at 08:53:57AM +0200, Jens Axboe wrote: > > > + if (wbc->sync_mode == WB_SYNC_ALL) > > > + bdi_wait_on_work_clear(&work); > > > } > > > > That doesn't work, you have to wait for on-stack work. So either we just > > punt and not do anything for WB_SYNC_NONE if the allocation fails, or we > > punt to stack and do the wait. Since it's a cleaning action and > > allocation fails, falling back to the stack and waiting seems like the > > most appropriate choice. > > True, the wait needs to be unconditional. Updated version below.
(did you forget that patch? it's not there).
> But now that I look at it, I wonder if we should even bother with it. > bdi_start_writeback is only used in WC_SYNC_NONE mode in > balance_dirty_pages. So if we really run so much out of memory that we > can't allocate the bdi_work we might just throttle and wait for the > flusher thread to do it's work. That would get rid of all the > special cases for the on-stack bdi_work instances.
Dunno, it feels a lot saner to always block there and ensure that we get the message across.
-- Jens Axboe
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