Performance issues with 8.0 ZFS and sendfile/lighttpd

[Urmas Lett]

gnukix at alltel.blackberry.com wrote:
> I can send in more documentation later but I am seeing severe zfs performance issues with lighttpd. Same machine using UFS will push 1gbit or more but same content and traffic load can not hit 200mbit. Ufs does around 3 megabytes/sec IO at 800mbit network but zfs pushes the disks into the ground with 50+ megabytes/sec dusk i/o. No compression no atime no checksums on zfs and still same IO levels. Ufs with soft updates and atime on. Orders of magnitude more disk IO... Like zfs isn't using cache or isn't coalescing disk reads or both. 
> 
> Has anyone else seen this or have any recommendations? Lighttpd config remains exactly the same as well FYI. Only difference is ufs vs zfs. 

Hi,

I can confirm this on FreeBSD 7.2-STABLE.

first run:
:~# wget -O /dev/null http://192.168.1.1/1000m.bin
--2009-11-04 15:36:15--  http://192.168.1.1/1000m.bin
Connecting to 192.168.1.1:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1048576000 (1000M) [application/octet-stream]
Saving to: `/dev/null'
100%[====================================>] 1,048,576,000 17.0M/s   in 
81s
2009-11-04 15:37:36 (12.3 MB/s) - `/dev/null' saved [1048576000/1048576000]

second run is even slower, cannot wait till end:
:~# wget -O /dev/null http://192.168.1.1/1000m.bin
--2009-11-04 15:40:00--  http://192.168.1.1/1000m.bin
Connecting to 192.168.1.1:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1048576000 (1000M) [application/octet-stream]
Saving to: `/dev/null'
71% [==========================>            ] 752,173,056 2.10M/s  eta 
2m 0s   ^C


After changing in lighttpd.conf
server.network-backend = "writev"

first run:
:~# wget -O /dev/null http://192.168.1.1/1000m.bin
--2009-11-04 15:47:51--  http://192.168.1.1/1000m.bin
Connecting to 192.168.1.1:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1048576000 (1000M) [application/octet-stream]
Saving to: `/dev/null'
100%[====================================>] 1,048,576,000 44.1M/s   in 
27s
2009-11-04 15:48:18 (37.2 MB/s) - `/dev/null' saved [1048576000/1048576000]

second & third run:

:~# wget -O /dev/null http://192.168.1.1/1000m.bin
--2009-11-04 15:48:20--  http://192.168.1.1/1000m.bin
Connecting to 192.168.1.1:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1048576000 (1000M) [application/octet-stream]
Saving to: `/dev/null'
100%[====================================>] 1,048,576,000  788M/s   in 
1.3s
2009-11-04 15:48:21 (788 MB/s) - `/dev/null' saved [1048576000/1048576000]

:~# wget -O /dev/null http://192.168.1.1/1000m.bin
--2009-11-04 15:48:24--  http://192.168.1.1/1000m.bin
Connecting to 192.168.1.1:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1048576000 (1000M) [application/octet-stream]
Saving to: `/dev/null'
100%[====================================>] 1,048,576,000  910M/s   in 
1.1s
2009-11-04 15:48:25 (910 MB/s) - `/dev/null' saved [1048576000/1048576000]

I have Intel 10GbE PCI-Express directly connected between two servers.

-- 
Urmas Lett

Tel:    +(372) 7 302 110
Fax:    +(372) 7 302 111
E-Mail: urmas.lett at eenet.ee