Messages in this thread | | | Date | Tue, 25 May 2004 14:16:22 -0700 | From | Andrew Morton <> | Subject | Re: 4g/4g for 2.6.6 |
| |
Rik van Riel <riel@redhat.com> wrote: > > On Tue, 25 May 2004, Rik van Riel wrote: > > > The point is, people like to run bigger workloads on > > bigger systems. Otherwise they wouldn't bother buying > > those bigger systems. > > Btw, you're right about the VMAs. Looking through customer > stuff a bit more the more common issues are low memory being > eaten by dentry / inode cache - which you can't always reclaim > due to files being open, and don't always _want_ to reclaim > because that could well be a bigger performance hit than the > 4:4 split.
I did some testing a year or two back with the normal zone wound down to a few hundred megs - filesytem benchmarks were *severely* impacted by the increased turnover rate of fs metadata pagecache and VFS caches. I forget the details, but it was "wow".
> The primary impact of the dentry / inode cache using memory > isn't lowmem exhaustion, btw. It's lowmem fragmentation. > > Fragmentation causes fork trouble (gone with the 4k stacks) > and trouble for the network layer and kiobuf allocation, > which still do need higher order allocations.
I'm suspecting we'll end up needing mempools (or something) of 1- and 2-order pages to support large-frame networking. I'm surprised there isn't more pressure to do something about this. Maybe people are increasing min_free_kbytes.
- 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/
| |