> -----Original Message----- > From: J. Bruce Fields [mailto:bfields@xxxxxxxxxxxx] > Sent: Friday, January 25, 2013 4:57 PM > To: Myklebust, Trond > Cc: Ben Myers; Olga Kornievskaia; linux-nfs@xxxxxxxxxxxxxxx; Jim Rees > Subject: Re: sunrpc: socket buffer size tuneable > > On Fri, Jan 25, 2013 at 09:45:12PM +0000, Myklebust, Trond wrote: > > > -----Original Message----- From: J. Bruce Fields > > > [mailto:bfields@xxxxxxxxxxxx] Sent: Friday, January 25, 2013 4:35 PM > > > To: Myklebust, Trond Cc: Ben Myers; Olga Kornievskaia; > > > linux-nfs@xxxxxxxxxxxxxxx; Jim Rees Subject: Re: sunrpc: socket > > > buffer size tuneable > > > > > > On Fri, Jan 25, 2013 at 09:29:09PM +0000, Myklebust, Trond wrote: > > > > > -----Original Message----- From: J. Bruce Fields > > > > > [mailto:bfields@xxxxxxxxxxxx] Sent: Friday, January 25, 2013 > > > > > 4:21 PM To: Myklebust, Trond Cc: Ben Myers; Olga Kornievskaia; > > > > > linux-nfs@xxxxxxxxxxxxxxx; Jim Rees Subject: Re: sunrpc: socket > > > > > buffer size tuneable > > > > > > > > > > On Fri, Jan 25, 2013 at 09:12:55PM +0000, Myklebust, Trond > > > > > wrote: > > > > > > > > > > Why is it not sufficient to clamp the TCP values of 'snd' and > > > > > > 'rcv' using > > > > > sysctl_tcp_wmem/sysctl_tcp_rmem? > > > > > > ...and clamp the UDP values using > > > > > sysctl_[wr]mem_min/sysctl_[wr]mem_max?. > > > > > > > > > > Yeah, I was just looking at that--so, Ben, something like: > > > > > > > > > > echo "1048576 1048576 4194304" > > > > > >/proc/sys/net/ipv4/tcp_wmem > > > > > > > > > > But I'm unclear on some of the details: do we need to set the > > > > > minimum or only the default? And does it need any more > > > > > allowance for protocol overhead? > > > > > > > > I meant adding a check either to svc_sock_setbufsize or to the 2 > > > > call-sites > > > that enforces the above limits. > > > > > > I lost you. > > > > > > It's not svc_sock_setbufsize that's setting too-small values, if > > > that's what you mean. > > > > > > > I understood that the problem was svc_udp_recvfrom() and > > svc_setup_socket() were using negative values in the calls to > > svc_sock_setbufsize(). Looking again at svc_setup_socket(), I don't > > see how that could do so, but svc_udp_recvfrom() definitely has > > potential to cause damage. > > Right, the changelog was confusing, the problem they're actually hitting is > with tcp. Looks like tcp autotuning is decreasing the send buffer below the > size we requested in svc_sock_setbufsize(). Yes. As far as I can tell, that is endemic unless you lock the sndbuf size. Grep for sk_stream_moderate_sndbuf(), and you'll see what I mean. Trond -- 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
