[Samba] Samba Transfer Efficiency (undocumented perf hint for Win7 gives 10X write speeds)
Linda W
samba at tlinx.org
Sun Jun 20 18:26:32 MDT 2010
I can share what I have, but won't claim they are optimal for
everyone. For win7, they give near theoretical performance on
writes (with win7 tuned correctly as well).
Will only mention a few pertinent items. Standard
disclaimers concerning your software, work load and hardware
all need to be considered when evaluating params.
Biggest thing is in reserving enough memory.
I just remeasured linear performance -- using a single task, using
'dd' to/from a server file of 1 or 4GB in size.
I also figured out my Win7 performance was way below par -- and
tried a WinXP performance improvement on it -- and had it work --
even though it's widely said around the net to no longer work in
Vista or above.
First the linux params, then the other params.
linux:
/proc/sys/net/ipv4
(same methods may work for ipv6, but haven't tested them)
Comparing my distro's defaults to my modified values:
*(don't know if this is important, as I don't think
congestion enters into play in my setup, but:)
default:
tcp_allowed_congestion_control=cubic reno
tcp_available_congestion_control=cubic reno
tcp_congestion_control=cubic
tcp_ecn=0
tcp_timestamps=1
mod:
tcp_allowed_congestion_control=htcp reno
tcp_available_congestion_control=htcp reno scalable
tcp_congestion_control=htcp
tcp_ecn=1
tcp_timestamps=0
Then memory for tcp:
default:
tcp_mem: 47136 62848 95272
tcp rmem 4096 87380 2011136
tcp wmem 4096 87380 2011136
mod:
tcp_mem 2097152 8338608 268435456
tcp_rmem 1048576 4194304 134217728
tcp_wmem 1048576 4194304 134217728
Also, in /etc/samba/smb.conf:
socket options = TCP_NODELAY IPTOS_LOWDELAY SO_SNDBUF=4194304 SO_RCVBUF=4194304
(also, not sure if they are as important, but also use:)
aio read size=65536
aio write size=65536
min recievefile size=65536
max xmit=66576
---
On my clients, under the HKLM/currentcontrolset, under
TcpIp/Parameters I have (both DWORDS):
TcpMaxWindowSize=1048576
GlobalMaxTcpWindowSize 1048576
AND I have those same two DWORDS under my active "Interface"
key (under Parameters). I looked for the one that corresponded
to my client's active interface.
-----------------------------------
Notes:
In writing up these params I did some benchmark testings.
Win7 (without the TCPMaxWindowSize) changes in the registry),
gave 10MB/s reads and 12MB/s writes.
WinXP (didn't already had those changes) came in at
35MB/s reads and 73MB/s writes.
Putting in the MaxWinSize words in my Win7 registry (though
several places around the net claim this param was no longer
used, from Vista on), gives:
70MB/s reads
108MB/s writes.
Note -- these are measured not just in terms of the execution
time of 'dd', but also looking at "xosview" running (actually
running remotely over X -- i.e. using up some of that file
transfer bandwidth!). I.e. Xosview showed 108MB/s when I measured
108MB/s in 'dd'. So it wasn't a related to cache timings.
Am glad you posted your question, as I wouldn't have experimented
with the TCPMaxWinSize -- as every place I looked claimed that param
was no longer used from Vista on -- so I had not previously tried it
(being gullible enough to believe all the sites that claimed it was
no longer supported. C'est la vi!).
Hope this helps,
Linda
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