Re: I/O blocked while dirty pages are being flushed
From: Fredrik Tolf
Date: Mon Mar 25 2013 - 03:31:57 EST
On Sun, 24 Mar 2013, Bart Van Assche wrote:
On 03/24/13 06:12, Fredrik Tolf wrote:
While this flush is running, I find that many a process goes into disk
sleep waiting for the flush to complete. This includes the process
manipulating the mmapped file whenever it tries to redirty a page
currently waiting to be flushed, but also, for instance, programs that
write() to log files (since, I guess, the buffer page backing the last
written portion of the log file is being flushed).
Had you already encountered this article: Jonathan Corbet, The trouble with
stable pages, March 13, 2012 (http://lwn.net/Articles/486311/) ?
I had not, but that certainly does seem to be the exact problem I'm
having. Thanks for the link; it was a very interesting read! Does anyone
know if any progress has been made since about any resolution of the
situation?
I notice linked mail threads with people saying that they have simply
removed the calls to wait_on_page_writeback to resolve their problems. Can
this still be considered safe, or have other systems than this
block-device checksumming started depending on stable pages since? Like
software RAID, for instance?
--
Fredrik Tolf
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