On Thursday 08 December 2005 18:01, Jeff Dike wrote: > On Thu, Dec 08, 2005 at 03:06:28PM +0100, Joel Palmius wrote: > > Are there any general recommendations for making throughput on UBDs more > > efficient? Such as kernel settings, recommended filesystems..? > > > > Doing an "emerge sync" inside an uml raises iowait to 100% and load to 7, > > making the machine more or less inaccessible. Just wondering if it's me > > having bad settings. > > I strongly suspect a bad interaction with the host I/O scheduler, although > I can't prove anything.
One OLS paper talked about using a special host elevator (without adding details), together with XFS on the host partition containing UBD files (because XFS is optimized for huge files), to better support UML's AIO. > The UML is just passing read/write requests to the > host and expecting them to be handled somewhat efficiently. > Using AIO helps (~25% on a kernel build), but I still see the same basic > symptoms (nothing running, everything in iowait). Tested with a CPU-hog running too? That's the test case we're interested into to see whether UML is performing blocking I/O calls or not. Also, the iowait is on the host or on the guest? I fear on the host, but I'd hope not. -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade ___________________________________ Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB http://mail.yahoo.it ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
