On Tue, Oct 06, 2015 at 04:24:43PM +0200, krautus@xxxxxxxxx wrote: > Dear List, nice to meet you :) > > First post, straight to the point: > I'm wrestling from few weeks with a problem: roundcube (a webmail client) takes too long to open a dovecot (pop/imap server) mailbox with many emails (files). > So, when such user has more than 10K emails, it takes around 1 minute to open the mailbox. > Meanwhile, I/O %util goes to 100% and bottlenecks the whole system. > > I've tried memcache(d) integration with roundcube but it doesn't eliminate the problem. > > OS is Debian Wheezy 32-bit, 16GB of ECC RAM and storage is a simple hardware raid-1 with a couple of sata2 hard disks. > I've just used mkfs.xfs (with no tuning) and no options while mounting (in fstab). > > It looks like the problem is the slow access to dentries and inodes, so I've set vfs_cache_pressure to 1, > forced buffering with few "find /var/mail > /dev/null" > and have it running like this from around 4 days. > Didn't help: slabs still gets flushed and opening folders is slow as before. > > Current slabtop usage shows: > 235352K used by xfs_inode > and > 49708K used by dentry > while I would expect to have at least 1 GB of xfs_inode and at least 200MB of dentry. > > So I'm asking you: > 1. is there a way to force dentries and inodes to stay in ram ? > 2. can I perhaps move dentries and inodes to a dedicated SSD ? > > I'm open to all possibilities, perhaps increase RAM ? > Upgrade to Debian Jessie and 64 bit ? ISTR that kernel data such as slabs cannot live in highmem, which means that dentries and slab cannot live in highmem. A 32bit kernel sets up ~900M of low memory and ~15G of highmem, which is probably why the kernel has to evict things and why you see such problems. A 64bit kernel sets up all the memory as lowmem, so the kernel can use all the memory for stuff like that. I'd give that a try first. --D > > Let me know if I can provide more info. > > > Thank you very much! > Mike > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
