On Fri, Apr 15, 2011 at 5:10 PM, Anthony Liguori <aligu...@us.ibm.com> wrote: > On 04/15/2011 10:34 AM, Christoph Hellwig wrote: >> >> On Fri, Apr 15, 2011 at 04:26:41PM +0100, Stefan Hajnoczi wrote: >>> >>> On Fri, Apr 15, 2011 at 4:05 PM, Christoph Hellwig<h...@lst.de> wrote: >>>> >>>> NAK. ?Just wait for the bloody NFS client fix to get in instead of >>>> adding crap like that. >>> >>> That's totally fine if NFS client will be fixed in the near future but >>> this doesn't seem likely: >>> >>> http://www.spinics.net/lists/linux-nfs/msg20462.html >> >> The code to use preadv/pwritev has been in qemu for over 2 years, >> and it took people to notice the NFS slowdown until now, so don't >> expect it to be fixed three days layer. >> >> I can't event see you in the relevent threads arguing for getting it >> fixed, so don't complain. > > In general, since we are userspace, we should try to run well on whatever > kernel we're on. > > What I don't like about this patch is that likelihood of false positives. > We check for Linux and for NFS but that means an old userspace is doing > unoptimal things on newer kernels. Even if we had a kernel version check, > if the fix gets backported to an older kernel, we'll still get a false > positive. > > Ideally, we'd be able to query the kernel to see whether we should bounce or > not. But AFAIK there is nothing even close to an interface to do this > today.
Bah, good point. I was planning to sneak in a uname() later but that really doesn't cut it due to backports/downstream. Stefan
