Suparna Bhattacharya <suparna@in.ibm.com> wrote:
>
> +extern int FASTCALL(aio_wait_on_page_bit(struct page *page, int bit_nr));
> +static inline int aio_wait_on_page_locked(struct page *page)
Oh boy.
There are soooo many more places where we can block:
- write() -> down(&inode->i_sem)
- read()/write() -> read indirect block -> wait_on_buffer()
- read()/write() -> read bitmap block -> wait_on_buffer()
- write() -> allocate block -> mark_buffer_dirty() ->
balance_dirty_pages() -> writer throttling
- write() -> allocate block -> journal_get_write_access()
- read()/write() -> update_a/b/ctime() -> journal_get_write_access()
- ditto for other journalling filesystems
- read()/write() -> anything -> get_request_wait()
(This one can be avoided by polling the backing_dev_info congestion
flags)
- read()/write() -> page allocator -> blk_congestion_wait()
- write() -> balance_dirty_pages() -> writer throttling
- probably others.
Now, I assume that what you're looking for here is an 80% solution, but it
seems that a lot more changes will be needed to get even that far.
And given that a single kernel thread per spindle can easily keep that
spindle saturated all the time, one does wonder "why try to do it this way at
all"?
-
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This archive was generated by hypermail 2b29 : Fri Mar 07 2003 - 22:00:27 EST