Messages in this thread Patch in this message | | | Date | Fri, 11 Mar 2005 07:10:35 +0100 | From | Andrea Arcangeli <> | Subject | 2.4 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/
| |