lkml.org 
[lkml]   [2005]   [Mar]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject2.4 fix for write throttling on x86 >1G
Hello Marcelo,

I've got a fix for you on 2.4. I got reports of stalls with heavy writes
on 2.4. There was a mistake in nr_free_buffer_pages. That function is
definitely meant _not_ to take highmem into account (dirty cache cannot
spread over highmem in 2.4 [even when on top of fs]). For unknown
reasons it was actually taking highmem into account. The code was
obviously meant to not take inot account see the GFP_USER and zonelist,
except it wasn't using the zonelist. That is a severe problem because
there will be no write throttling at all, and no bdflush wakeup either.

This should fix it, though my compiler fails to compile 2.4, so it's not
immediate to verify it. If any problem showup I'll post a followup.

This is a noop for all systems <800M (1G shouldn't be noticeable
either). This is why most people can't notice.

Thanks.

Signed-off-by: Andrea Arcangeli <andrea@suse.de>

--- 2.4.23aa3/mm/page_alloc.c.~1~ 2004-07-04 02:09:42.000000000 +0200
+++ 2.4.23aa3/mm/page_alloc.c 2005-03-11 07:00:23.000000000 +0100
@@ -656,7 +656,7 @@ unsigned int nr_free_buffer_pages (void)
class_idx = zone_idx(zone);

sum += zone->nr_cache_pages;
- for (zone = pgdat->node_zones; zone < pgdat->node_zones + MAX_NR_ZONES; zone++) {
+ for (; zone; zone = *zonep++) {
int free = zone->free_pages - zone->watermarks[class_idx].high;
if (free <= 0)
continue;
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2005-03-22 14:11    [W:0.054 / U:0.332 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site