Re: [RFC] changes to buffer.c (was Test12 ll_rw_block error)

[Marcelo Tosatti <marcelo@conectiva.com.br>]

On Fri, 22 Dec 2000, Chris Mason wrote:

> 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).

If we use ll_rw_block directly on buffers of anonymous pages
(page->mapping == &anon_space_mapping) instead using
dirty_list_writepage() (which will end up calling block_write_anon_page)
we can fix the buffer flushtime issue.

> 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.

At writepage() context we do not know if we should care about the
flushtime.

> 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?

Could you please send me your latest patch ?

Thanks

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