Re: [PATCH] mm/vmscan: change generic_file_write() comment to do_sync_write()

[Nikita Danilov <danilov@gmail.com>]

2009/8/26 Vincent Li <macli@brc.ubc.ca>

[...]

> Thank you for the explaintion!
>
>        * If this process is currently in generic_file_write() against
>        * this page's queue, we can perform writeback even if that
>        * will block.
>
> So my interpretation for the comment is that if the current process is
> already in __generic_file_aio_write against the page's queue, The page
> claim path code can still perfom writeback even if the __generic_file_aio_write
> will block. Am I right?

Yes. The idea is that a heavy writer causing a lot of page allocations
should wait for the queue to drain, thus throttling itself; while a
thread that triggeres direct reclaim occasionally (i.e., not from the
main write path) shouldn't be blocked on the transput incurred by
somebody else.

Nikita.

>
>
>
> Vincent Li
> Biomedical Research Center
> University of British Columbia

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