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SubjectRe: __lock_page calls run_task_queue(&tq_disk) unecessarily?

Btw ___wait_on_page() does something similar.

Here goes the patch for both __lock_page() and ___wait_on_page().


--- linux/mm/filemap.c.orig Mon Feb 19 23:51:02 2001
+++ linux/mm/filemap.c Mon Feb 19 23:51:33 2001
@@ -611,11 +611,11 @@

add_wait_queue(&page->wait, &wait);
do {
- sync_page(page);
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (!PageLocked(page))
break;
- run_task_queue(&tq_disk);
+
+ sync_page(page);
schedule();
} while (PageLocked(page));
tsk->state = TASK_RUNNING;
@@ -633,10 +633,9 @@

add_wait_queue_exclusive(&page->wait, &wait);
for (;;) {
- sync_page(page);
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (PageLocked(page)) {
- run_task_queue(&tq_disk);
+ sync_page(page);
schedule();
continue;
}

On Mon, 19 Feb 2001, Marcelo Tosatti wrote:

>
> Hi Linus,
>
> Take a look at __lock_page:
>
> static void __lock_page(struct page *page)
> {
> struct task_struct *tsk = current;
> DECLARE_WAITQUEUE(wait, tsk);
>
> add_wait_queue_exclusive(&page->wait, &wait);
> for (;;) {
> sync_page(page);
> set_task_state(tsk, TASK_UNINTERRUPTIBLE);
> if (PageLocked(page)) {
> run_task_queue(&tq_disk);
> schedule();
> continue;
> }
> if (!TryLockPage(page))
> break;
> }
> tsk->state = TASK_RUNNING;
> remove_wait_queue(&page->wait, &wait);
> }
>
>
> Af a process sleeps in __lock_page, sync_page() will be called even if the
> page is already unlocked. (block_sync_page(), the sync_page routine for
> generic block based filesystem calls run_task_queue(&tq_disk)).
>
> I don't see any problem if we remove the run_task_queue(&tq_disk) and put
> sync_page(page) there instead, removing the other sync_page(page) at the
> beginning of the loop.
>
> Comments?
>
> -
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