On 03/22/2016 03:40 PM, Jens Axboe wrote:
On 03/22/2016 03:34 PM, Dave Chinner wrote:
On Tue, Mar 22, 2016 at 11:55:16AM -0600, Jens Axboe wrote:
If you call sync, the initial call to wakeup_flusher_threads() ends up
calling wb_start_writeback() with reason=WB_REASON_SYNC, but
wb_start_writeback() always uses WB_SYNC_NONE as the writeback mode.
Ensure that we use WB_SYNC_ALL for a sync operation.
This seems wrong to me. We want background write to happen as
quickly as possible and /not block/ when we first kick sync.
It's not going to block. wakeup_flusher_threads() async queues writeback
work through wb_start_writeback().
For block here, you mean the async work ending up doing
wait_on_page_writeback() because we're doing WB_SYNC_ALL instead of
WB_SYNC_NONE?
And if so:
The latter blocking passes of sync use WB_SYNC_ALL to ensure that we
block waiting for all remaining IO to be issued and waited on, but
the background writeback doesn't need to do this.
why not have it do that?
--
Jens Axboe
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