This modifies balance_dirty_pages() not to block the caller when
the amount of Dirty+Writeback is less than `vm.dirty_limit_ratio'
percent of the total memory.
In that case, the generator of the dirty pages are throttled in the
write-requests-queue of the backing device.
throttle_vm_writeout() is also changed to calculate the threshold from
the new limit provided by modified get_dirty_limits().
Signed-off-by: Tomoki Sekiyama <[EMAIL PROTECTED]>
Signed-off-by: Yuji Kakutani <[EMAIL PROTECTED]>
---
mm/page-writeback.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)
Index: linux-2.6.21-rc3-mm2/mm/page-writeback.c
===================================================================
--- linux-2.6.21-rc3-mm2.orig/mm/page-writeback.c
+++ linux-2.6.21-rc3-mm2/mm/page-writeback.c
@@ -219,12 +219,15 @@ get_dirty_limits(long *pbackground, long
* balance_dirty_pages() must be called by processes which are generating dirty
* data. It looks at the number of dirty pages in the machine and will force
* the caller to perform writeback if the system is over `vm_dirty_ratio'.
+ * If the caller couldn't writeback `write_chunk' pages and we're over
+ * `dirty_limit', the caller will be blocked in congestion_wait().
* If we're over `background_thresh' then pdflush is woken to perform some
* writeout.
*/
static void balance_dirty_pages(struct address_space *mapping)
{
long nr_reclaimable;
+ long nr_dirty;
long background_thresh;
long dirty_thresh;
long dirty_limit;
@@ -246,9 +249,9 @@ static void balance_dirty_pages(struct a
&dirty_limit, mapping);
nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
- if (nr_reclaimable + global_page_state(NR_WRITEBACK) <=
- dirty_thresh)
- break;
+ nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK);
+ if (nr_dirty <= dirty_thresh)
+ break;
if (!dirty_exceeded)
dirty_exceeded = 1;
@@ -265,20 +268,21 @@ static void balance_dirty_pages(struct a
&dirty_limit, mapping);
nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
- if (nr_reclaimable +
- global_page_state(NR_WRITEBACK)
- <= dirty_thresh)
- break;
+ nr_dirty = nr_reclaimable +
+ global_page_state(NR_WRITEBACK);
+ if (nr_dirty <= dirty_thresh)
+ break;
pages_written += write_chunk - wbc.nr_to_write;
if (pages_written >= write_chunk)
break; /* We've done our duty */
+ if (nr_dirty <= dirty_limit)
+ break; /* no more dirty pages on bdi */
}
congestion_wait(WRITE, HZ/10);
}
- if (nr_reclaimable + global_page_state(NR_WRITEBACK)
- <= dirty_thresh && dirty_exceeded)
- dirty_exceeded = 0;
+ if (nr_dirty <= dirty_thresh && dirty_exceeded)
+ dirty_exceeded = 0;
if (writeback_in_progress(bdi))
return; /* pdflush is already working this queue */
@@ -372,10 +376,10 @@ void throttle_vm_writeout(gfp_t gfp_mask
* Boost the allowable dirty threshold a bit for page
* allocators so they don't get DoS'ed by heavy writers
*/
- dirty_thresh += dirty_thresh / 10; /* wheeee... */
+ dirty_limit += dirty_limit / 10; /* wheeee... */
if (global_page_state(NR_UNSTABLE_NFS) +
- global_page_state(NR_WRITEBACK) <= dirty_thresh)
+ global_page_state(NR_WRITEBACK) <= dirty_limit)
break;
congestion_wait(WRITE, HZ/10);
}
-
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