I've recently been trying to track down the root cause of my server's persistent issue of thrashing horribly after being left inactive. It seems that the issue is likely my nightly backup schedule (using rsync) which traverses my entire 50GB home directory. I was surprised to find that rsync does not use fadvise to notify the kernel of its use-once data usage pattern. It looks like a patch[1] was written (although never merged, it seems) incorporating fadvise support, but I found its implementation rather odd, using mincore() and FADV_DONTNEED to kick out only regions brought in by rsync. It seemed to me the simpler and more appropriate solution would be to simply flag every touched file with FADV_NOREUSE and let the kernel manage automatically expelling used pages. After looking deeper into the kernel implementation[2] of fadvise() the reason for using DONTNEED became more apparant. It seems that the kernel implements NOREUSE as a noop. A little googling revealed[3] that I not the first person to encounter this limitation. It looks like a few folks[4] have discussed addressing the issue in the past, but nothing has happened as of 2.6.36. Are there plans to implement this functionality in the near future? It seems like the utility of fadvise is severely limited by lacking support for NOREUSE. Cheers, - Ben [1] http://insights.oetiker.ch/linux/fadvise.html [2] http://lxr.free-electrons.com/source/mm/fadvise.c?a=avr32 [3] https://issues.apache.org/jira/browse/CASSANDRA-1470 http://chbits.blogspot.com/2010/06/lucene-and-fadvisemadvise.html [4] http://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg179576.html http://lkml.indiana.edu/hypermail/linux/kernel/0807.2/0442.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>