Messages in this thread | | | Subject | RE: [PATCH][1/2] adjust dirty threshold for lowmem-only mappings | Date | Mon, 20 Dec 2004 10:46:48 -0600 | From | <> |
| |
> On Mon, 20 Dec 2004, Rik van Riel wrote: > >> Simply running "dd if=/dev/zero of=/dev/hd<one you can miss>" >> will result in OOM kills, with the dirty pagecache >> completely filling up lowmem. This patch is part 1 to >> fixing that problem. > > What I forgot to say is that in order to trigger this OOM > Kill the dirty_limit of 40% needs to be more memory than > what fits in low memory. So this will work on x86 with > 4GB RAM, since the dirty_limit is 1.6GB, but the block > device cache cannot grow that big because it is restricted > to low memory. > > This has the effect of all low memory being tied up in > Dirty page cache and userspace try_to_free_pages() skipping > the writeout of these pages because the block device is > congested.
I am just confirming that this is a real problem. The problem more frequently shows up with block sizes above 4k on the dd and also showed up on some platforms with just a mke2fs on a slower device such as a USB hard drive.
Rik's patch has solved the issue and has been running under stress (via ctcs) over the weekend without failure.
Regards, Robert
- 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/
| |