Date: Wed, 17 Nov 2004 16:33:59 -0700 From: Scott Long <scottl@freebsd.org> To: Emanuel Strobl <Emanuel.Strobl@gmx.net> Cc: freebsd-stable@freebsd.org Subject: Re: serious networking (em) performance (ggate and NFS) problem Message-ID: <419BDFE7.9090402@freebsd.org> In-Reply-To: <200411172357.47735.Emanuel.Strobl@gmx.net> References: <200411172357.47735.Emanuel.Strobl@gmx.net>
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Emanuel Strobl wrote: > Dear best guys, > > I really love 5.3 in many ways but here're some unbelievable transfer rates, > after I went out and bought a pair of Intel GigaBit Ethernet Cards to solve > my performance problem (*laugh*): > > (In short, see *** below) > > Tests were done with two Intel GigaBit Ethernet cards (82547EI, 32bit PCI > Desktop adapter MT) connected directly without a switch/hub and "device > polling" compiled into a custom kernel with HZ set to 256 and > kern.polling.enabled set to "1": > > LOCAL: > (/samsung is ufs2 on /dev/ad4p1, a SAMSUNG SP080N2) > test3:~#7: dd if=/dev/zero of=/samsung/testfile bs=16k > ^C10524+0 records in > 10524+0 records out > 172425216 bytes transferred in 3.284735 secs (52492882 bytes/sec) > -> > ^^^^^^^^ ~ 52MB/s > NFS(udp,polling): > (/samsung is nfs on test3:/samsung, via em0, x-over, polling enabled) > test2:/#21: dd if=/dev/zero of=/samsung/testfile bs=16k > ^C1858+0 records in > 1857+0 records out > 30425088 bytes transferred in 8.758475 secs (3473788 bytes/sec) > -> ^^^^^^^ ~ 3,4MB/s > > This example shows that using NFS over GigaBit Ethernet decimates performance > by the factor of 15, in words fifteen! > > GGATE with MTU 16114 and polling: > test2:/dev#28: ggatec create 10.0.0.2 /dev/ad4p1 > ggate0 > test2:/dev#29: mount /dev/ggate0 /samsung/ > test2:/dev#30: dd if=/dev/zero of=/samsung/testfile bs=16k > ^C2564+0 records in > 2563+0 records out > 41992192 bytes transferred in 15.908581 secs (2639594 bytes/sec) > -> ^^^^^^^ ~ 2,6MB/s > > GGATE without polling and MTU 16114: > test2:~#12: ggatec create 10.0.0.2 /dev/ad4p1 > ggate0 > test2:~#13: mount /dev/ggate0 /samsung/ > test2:~#14: dd if=/dev/zero of=/samsung/testfile bs=128k > ^C1282+0 records in > 1281+0 records out > 167903232 bytes transferred in 11.274768 secs (14891945 bytes/sec) > -> ^^^^^^^^ ~ 15MB/s > .....and with 1m blocksize: > test2:~#17: dd if=/dev/zero of=/samsung/testfile bs=1m > ^C61+0 records in > 60+0 records out > 62914560 bytes transferred in 4.608726 secs (13651182 bytes/sec) > -> ^^^^^^^^ ~ 13,6MB/s > > I can't imagine why there seems to be a absolute limit of 15MB/s that can be > transfered over the network > But it's even worse, here two excerpts of NFS (udp) with jumbo Frames > (mtu=16114): > test2:~#23: mount 10.0.0.2:/samsung /samsung/ > test2:~#24: dd if=/dev/zero of=/samsung/testfile bs=1m > ^C89+0 records in > 88+0 records out > 92274688 bytes transferred in 13.294708 secs (6940708 bytes/sec) > -> ^^^^^^^ ~7MB/s > .....and with 64k blocksize: > test2:~#25: dd if=/dev/zero of=/samsung/testfile bs=64k > ^C848+0 records in > 847+0 records out > 55508992 bytes transferred in 8.063415 secs (6884055 bytes/sec) > > And with TCP-NFS (and Jumbo Frames): > test2:~#30: mount_nfs -T 10.0.0.2:/samsung /samsung/ > test2:~#31: dd if=/dev/zero of=/samsung/testfile bs=64k > ^C1921+0 records in > 1920+0 records out > 125829120 bytes transferred in 7.461226 secs (16864403 bytes/sec) > -> ^^^^^^^^ ~ 17MB/s > > Again NFS (udp) but with MTU 1500: > test2:~#9: mount_nfs 10.0.0.2:/samsung /samsung/ > test2:~#10: dd if=/dev/zero of=/samsung/testfile bs=8k > ^C12020+0 records in > 12019+0 records out > 98459648 bytes transferred in 10.687460 secs (9212633 bytes/sec) > -> ^^^^^^^ ~ 10MB/s > And TCP-NFS with MTU 1500: > test2:~#12: mount_nfs -T 10.0.0.2:/samsung /samsung/ > test2:~#13: dd if=/dev/zero of=/samsung/testfile bs=8k > ^C19352+0 records in > 19352+0 records out > 158531584 bytes transferred in 12.093529 secs (13108794 bytes/sec) > -> ^^^^^^^^ ~ 13MB/s > > GGATE with default MTU of 1500, polling disabled: > test2:~#14: dd if=/dev/zero of=/samsung/testfile bs=64k > ^C971+0 records in > 970+0 records out > 63569920 bytes transferred in 6.274578 secs (10131346 bytes/sec) > -> ^^^^^^^^ ~ 10M/s > > > Conclusion: > > *** > > - It seems that GEOM_GATE is less efficient with GigaBit (em) than NFS via TCP > is. > > - em seems to have problems with MTU greater than 1500 > > - UDP seems to have performance disadvantages over TCP regarding NFS which > should be vice versa AFAIK > > - polling and em (GbE) with HZ=256 is definitly no good idea, even 10Base-2 > can compete You should be setting HZ to 1000 or higher. > > - NFS over TCP with MTU of 16114 gives the maximum transferrate for large > files over GigaBit Ethernet with a value of 17MB/s, a quarter of what I'd > expect with my test equipment. > > - overall network performance (regarding large file transfers) is horrible > > Please, if anybody has the knowledge to dig into these problems, let me know > if I can do any tests to help getting ggate and NFS useful in fast 5.3-stable > environments. if_em in 5.3 has a large performance penalty in the common case due to a programming error. I fixed it in 6-CURRENT and 5.3-STABLE. You might want to try updating to the RELENG_5 branch to see if you get better results. Scott
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