----- Original Message ---- > From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > To: Martin Knoblauch <knobi@xxxxxxxxxxxx> > Cc: Greg Banks <gnb@xxxxxxxxxxxxxxxxx>; linux-nfs list <linux-nfs@xxxxxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx > Sent: Thursday, September 18, 2008 10:18:18 AM > Subject: Re: [RFC][Resend] Make NFS-Client readahead tunable > > On Thu, 18 Sep 2008 00:42:58 -0700 (PDT) Martin Knoblauch > wrote: > > > ----- Original Message ---- > > > > > From: Andrew Morton > > > To: Greg Banks > > > Cc: Martin Knoblauch ; linux-nfs list > ; linux-kernel@xxxxxxxxxxxxxxx > > > Sent: Thursday, September 18, 2008 5:13:34 AM > > > Subject: Re: [RFC][Resend] Make NFS-Client readahead tunable > > > > > > On Thu, 18 Sep 2008 11:42:54 +1000 Greg Banks wrote: > > > > > > > I think having a tunable for client readahead is an excellent idea, > > > > although not to solve your particular problem. The SLES10 kernel has a > > > > patch which does precisely that, perhaps Neil could post it. > > > > > > > > I don't think there's a lot of point having both a module parameter and > > > > a sysctl. > > > > > > mount -o remount,readahead=42 > > > > [root@lpsdm52 ~]# mount -o remount,readahead=42 /net/spsdms/fs13 > > Bad nfs mount parameter: readahead > > [root@lpsdm52 ~]# mount -o readahead=42 /net/spsdms/fs13 > > Bad nfs mount parameter: readahead > > > > > > I assume the reply was meant to say that the correct way of introducing a > modifyable readahead size is to implement it as a mount option ? :-) > > Yes. > :-) > > I considered it, but it seems to be more intrusive than the workaround patch. > It also needs changes to userspace tools - correct? > > No. mount(8) will pass unrecognised options straight down into the > filesystem driver. > Has that always been the case, or is it a recent change? I have to support RHEL4 userland, which is not really new. > It's better this way - it allows the tunable to be set on a per-mount > basis rather than machine-wide. > No question about that. I just thought it to be to complicated. Maybe I erred. > Note that for block devices, readahead is a per-backing_dev_info thing > (and a backing_dev_info has a 1:1 relationship to a disk drive for sane > setups). > > And the NFS client maintains a backing_dev_info, which appears to map > onto a server, so making the NFS readahead a per-backing_dev_info (ie: > per server) thing might make sense. Maybe nfs makes per-server information > manipulatable down in sysfs somewhere.. I believe Peter wanted to add per bdi stuff for nfs some time ago. Not sure what came out of it. Cheers Martin -- 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
