Messages in this thread |  | | Date | Fri, 22 Dec 2000 18:18:51 -0500 | From | Chris Mason <> | Subject | Re: [RFC] changes to buffer.c (was Test12 ll_rw_block error) |
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On Friday, December 22, 2000 17:52:28 -0200 Marcelo Tosatti <marcelo@conectiva.com.br> wrote:
> There is one more nasty issue to deal with. > > You only want to take into account the buffer flushtime if > "check_flushtime" parameter is passed as true to flush_dirty_buffers > (which is done by kupdate). > > Thinking a bit more about the issue, I dont see any reason why we want to > write all buffers of an anonymous page at > sync_buffers/flush_dirty_buffers. > > I think we could simply write the buffer with ll_rw_block() if the page > which this buffer is sitting on does not have mapping->a_ops->writepage > operation defined. >
It is enough to leave buffer heads we don't flush on the dirty list (and redirty the page), they'll get written by a future loop through flush_dirty_pages, or by page_launder. We could use ll_rw_block instead, even though anon pages do have a writepage with this patch (just check if page->mapping == &anon_space_mapping).
There are lots of things we could try here, including some logic inside block_write_anon_page to check the current memory pressure/dirty levels to see how much work should be done.
I'll play with this a bit, but more ideas would be appreciated.
BTW, recent change to my local code was to remove the ll_rw_block call from sync_page_buffers. It seemed cleaner than making try_to_free_buffers understand that sometimes writepage will be called, and sometimes the page will end up unlocked because of it....comments?
-chris
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