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SubjectRe: test11-pre6
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Linus,

You forgot about wakeup_bdflush(1) stuff.

Here is the patch again (against test10).
===============================================================
There are several places where schedule() is called after wakeup_bdflush(1)
is called. This is completely unnecessary, since wakeup_bdflush(1) already
gave up the control, and when the control is returned to the calling thread
who called wakeup_bdflush(1), it should just go on. Calling schedule()
after wakeup_bdflush(1) will make the calling thread give up control again.
This is a problem for some of those latency sensitive benchmarks (like SPEC
SFS) and applications.

============
diff -ruN mm.orig/highmem.c mm.opt/highmem.c
--- mm.orig/highmem.c Wed Oct 18 14:25:46 2000
+++ mm.opt/highmem.c Fri Nov 10 17:51:39 2000
@@ -310,8 +310,6 @@
bh = kmem_cache_alloc(bh_cachep, SLAB_BUFFER);
if (!bh) {
wakeup_bdflush(1); /* Sets task->state to TASK_RUNNING */
- current->policy |= SCHED_YIELD;
- schedule();
goto repeat_bh;
}
/*
@@ -324,8 +322,6 @@
page = alloc_page(GFP_BUFFER);
if (!page) {
wakeup_bdflush(1); /* Sets task->state to TASK_RUNNING */
- current->policy |= SCHED_YIELD;
- schedule();
goto repeat_page;
}
set_bh_page(bh, page, 0);
diff -ruN fs.orig/buffer.c fs.opt/buffer.c
--- fs.orig/buffer.c Thu Oct 12 14:19:32 2000
+++ fs.opt/buffer.c Fri Nov 10 20:05:44 2000
@@ -707,11 +707,8 @@
*/
static void refill_freelist(int size)
{
- if (!grow_buffers(size)) {
+ if (!grow_buffers(size))
wakeup_bdflush(1); /* Sets task->state to TASK_RUNNING */
- current->policy |= SCHED_YIELD;
- schedule();
- }
}

void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void
*private)
==============================

Ying Chen

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