On Wed, 31 May 2006 14:45:13 -0700 Ben Greear <[EMAIL PROTECTED]> wrote:
> Ok, I think I found the problem. It appears to be at least partially > self-inflicted. I was modifying the kernel buffer settings via /proc/* > to improve performance. I noticed that when I used kernel-defaults, > the TCP connection hangs stopped (and ran ~20% slower). My personal opinion > is that this is still a bug somewhere in TCP, but at least I have a > work-around. If you set bogus values, you can end up consuming all the memory on your system. > Since these settings appear somewhat delicate, it might be nice if > the kernel could warn about configurations that could cause TCP deadlocks > and such. > There is little or no range checking on most all sysctl values. Whether or not that is a good thing is debatable. > My old settings that exhibitted the problem were: > > my $netdev_max_backlog = 5000; This only matters for non-NAPI devices. > my $wmem_max = 4096000; > my $wmem_default = 128000; > my $rmem_max = 8096000; > my $rmem_default = 128000; > > my $tcp_rmem_min = 4096; > my $tcp_rmem_default = 256000; Receiver auto-tuning makes setting this unnecessary in most cases. > my $tcp_rmem_max = 30000000; > > my $tcp_wmem_min = 4096; > my $tcp_wmem_default = 256000; That's too big with current auto-tuning. > my $tcp_wmem_max = 30000000; > > my $tcp_mem_lo = 20000000; > my $tcp_mem_pressure = 30000000; > my $tcp_mem_high = 60000000; > > > The new settings that appear to work around the TCP connection hang, > and still give decent performance are below. Documentation being thin, > I used the suggested values in Documentation/networking/ixgb.txt as > hints: Settings don't belong in this Documentation file because it a general thing not specific to that hardware. > my $netdev_max_backlog = 30000; > my $wmem_max = 524287; > my $wmem_default = 128000; > my $rmem_max = 524287; > my $rmem_default = 128000; > > my $tcp_rmem_min = 4096; > my $tcp_rmem_default = 256000; > my $tcp_rmem_max = 5000000; > > my $tcp_wmem_min = 4096; > my $tcp_wmem_default = 256000; > my $tcp_wmem_max = 5000000; > > my $tcp_mem_lo = 10000000; > my $tcp_mem_pressure = 20000000; > my $tcp_mem_high = 30000000; > > Thanks, > Ben > - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
