lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 11 Nov 2009 16:19:37 +0100 From: Tobias Diedrich <ranma+kernel@...edrich.de> To: linux-kernel@...r.kernel.org Cc: linux-mm@...ck.org Subject: posix_fadvise/WILLNEED synchronous on fuse/sshfs instead of async? While trying to use posix_fadvise(...POSIX_FADVISE_WILLNEED) to implement userspace read-ahead (with a bigger read-ahead window than the kernel default) I found that if the underlying filesystem is fuse/sshfs posix_fadvise is no longer doing asynchronous reads: strace -tt with mnt/testfile on sshfs and server with very slow upstream (ADSL): 5345 00:00:17.334209 open("mnt/testfile", O_RDONLY|O_LARGEFILE) = 3 5345 00:00:18.011383 _llseek(3, 0, [3544379], SEEK_END) = 0 5345 00:00:18.011626 _llseek(3, 0, [0], SEEK_SET) = 0 5345 00:00:18.012393 fadvise64_64(3, 0, 1048576, POSIX_FADV_WILLNEED) = 0 5345 00:01:02.438097 write(1, "[file] File size is 3544379 byte"..., 34) = 34 Note that fadvise takes 40 seconds... Is this expected behaviour? I would have expected that fadvise is always asynchronous and I could rely on the call to return almost immediately. -- Tobias PGP: http://8ef7ddba.uguu.de -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists