On Sat, 3 Mar 2007 14:58:48 -0800 "Ray Lee" <[EMAIL PROTECTED]> wrote:
> On 3/3/07, Andrew Morton <[EMAIL PROTECTED]> wrote: > > It is to address the "waah, backups fill my memory with pagecache" and the > > "waah, updatedb swapped everything out" and the "waah, copying a DVD > > gobbled all my memory" problems. > > Is the updatedb problem really due to pagecache? It's a combination of pagecache, slab cache and of course contention for the disk. In my experience the latter preponderates: the disk is sekeing like mad and I can't get its attention. Others report lots of swapout, which will be a combination of slab and pagecache, varying degrees of each. > > When running > > > > pagecache-management.sh dd if=100-mb-file of=foo > > or > > pagecache-management.sh cp -a /usr/src/linux-2.6.20 /usr/src/foo > > > > the amount of pagecache in the machine is pretty much unaltered. Maybe a > > megabyte of additional cache in the second case, because of ext3 indirect > > blocks. > > [EMAIL PROTECTED]:~/work/home/pagecache-management$ grep ext3_i > /proc/slabinfo; ./pagecache-management.sh sudo updatedb; grep ext3_i > /proc/slabinfo > ext3_inode_cache 21024 23722 1584 2 1 : tunables 24 12 > 0 : slabdata 11861 11861 0 > ext3_inode_cache 41332 41332 1584 2 1 : tunables 24 12 > 0 : slabdata 20666 20666 0 > [EMAIL PROTECTED]:~/work/home/pagecache-management$ echo $(( 1584 * > (41332-21024) )) > 32167872 If 32 MB is the whole lot then by eliminating pagecache, we just solved the problem. But perhaps you instantiated a lot more VFS cache and all you're seeing there is the leftovers. > Or is there a /proc/sys/vm/* knob that can be tweaked for this > before/after the updatedb? /proc/sys/vm/vfs_cache_pressure should help. I don't recall anyone reporting its effects with updatedb. > But yeah, I for one would happily submit patches to upstream authors > to address this there. There's no reason code should be making the > kernel guess its intention on these things. I think so. We're dealing with super-special cases here and often trying to fix those in-kernel will degrade other, often more common cases. <wonders about sys_reclaim_dentry(const char *pathname)> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
