Perhaps the use of a heuristic that enables readdirplus only after the application has shown that it is interested in the attributes for each entry in the directory? Thus, if the application does readdir()/stat()/stat()/stat()/readdir()/... then the NFS client could use readdirplus to fill the caches. If the application is just reading the directory and looking at the names, then the client could just use readdir. ps -----Original Message----- From: linux-nfs-owner@xxxxxxxxxxxxxxx [mailto:linux-nfs-owner@xxxxxxxxxxxxxxx] On Behalf Of NeilBrown Sent: Wednesday, March 16, 2011 12:55 AM To: Trond Myklebust; Bryan Schumaker Cc: linux-nfs@xxxxxxxxxxxxxxx Subject: Use of READDIRPLUS on large directories Hi Trond / Bryan et al. Now that openSUSE 11.4 is out I have started getting a few reports of regressions that can be traced to commit 0715dc632a271fc0fedf3ef4779fe28ac1e53ef4 Author: Bryan Schumaker <bjschuma@xxxxxxxxxx> Date: Fri Sep 24 18:50:01 2010 -0400 NFS: remove readdir plus limit We will now use readdir plus even on directories that are very large. Signed-off-by: Bryan Schumaker <bjschuma@xxxxxxxxxx> Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> This particularly affects users with their home directory over NFS, and with largish maildir mail folders. Where it used to take a smallish number of seconds for (e.g.) xbiff to start up and read through the various directories, it now takes multiple minutes. I can confirm that the slow down is due to readdirplus by mounting the filesystem with nordirplus. While I can understand that there are sometime benefits in using readdirplus for very large directories, there are also obviously real costs. So I think we have to see this patch as a regression that should be reverted. It would quite possibly make sense to create a tunable (mount option or sysctl I guess) to set the max size for directories to use readdirplus, but I think it really should be an opt-in situation. [[ It would also be really nice if the change-log for such a significant change contained a little more justification.... :-( ]] Thoughts? Thanks, NeilBrown -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
