PHWinfo - Afficher un message - Gigabit Ethernet, and Linux -- first observations

12/09/2007, 15h08

On 12 Sep 2007 12:52:09 GMT, General Schvantzkoph <schvantzkoph@yahoo.com> wrote:

>On Wed, 12 Sep 2007 01:14:07 -0400, Michael Mol wrote:

>> Ignoramus26973 wrote:
>>> I installed a gigabit network switch and a gigabit enabled laptop wifi
>>> adapter (with gigabit, obviously, available on ethernet ports only) in
>>> my house.
>>>
>>> Two computers in my home are connected to the switch and one (laptop)
>>> to the wifi adaptor.
>>>
>>> The highest possible speed of a gigabit connection is about 111
>>> megabytes per second.
>>>
>>> Naturally, I did some tests with a noncompressible 1 gigabyte long file
>>> (fragment of some gzipped file exactly one GB long).
>>>
>>> My first test was to scp files from one computer on the switch to
>>> another. Here, I was disappointed as the highest speed was only 22
>>> megabytes per second one way and 46 another way. About 20 and 40
>>> percent of maximum.
>>>
>>> Then I tried using HTTP to transfer the same file (both computers are
>>> webservers). To my huge surprise, it made a world of difference and the
>>> transfer speed was 111 or so megabytes per second.
>>>
>>> So, now I have a dilemma, I have a fast pipe, but scp is not fast
>>> enough (given my CPU) to encrypt/decrypt so much data.
>>>
>>> I tried something else, which is doing wc -l on a NFS mounted drive
>>> (same two computers). It was UNBELIEVABLY slow and the load average on
>>> the NFS server shot WAY up. Transferring a 336 MB file took 157
>>> seconds, or about e megabytes per second (vs 111 mbps that I achieved
>>> with HTTP).
>>
>> So, about 2.7 MB/s? :-)
>>
>>
>>> So, the conclusion is, HTTP is fast (no wonder), SSH is "medium", and
>>> NFS is "slow, very bad".
>>
>> I ran into a similar problem with NFS ages back. Turns out you can
>> largely fix it by configuring NFS to increase the packet size. Been a
>> few years since I did anything with NFS, though, so you'll have to look
>> through the docs. I hear they use it in computer clusters, so it can't
>> be slow in *all* cases.

>How do you configure NFS to increase the packet size? Also are you
>talking about NFS V4 or V3?

when you mount it. Why didn't you just google for "nfs packet size"?

12/09/2007, 15h08	#4
AZ Nomad Messages: n/a Hébergeur:	Re: Gigabit Ethernet, and Linux -- first observations On 12 Sep 2007 12:52:09 GMT, General Schvantzkoph <schvantzkoph@yahoo.com> wrote: >On Wed, 12 Sep 2007 01:14:07 -0400, Michael Mol wrote: >> Ignoramus26973 wrote: >>> I installed a gigabit network switch and a gigabit enabled laptop wifi >>> adapter (with gigabit, obviously, available on ethernet ports only) in >>> my house. >>> >>> Two computers in my home are connected to the switch and one (laptop) >>> to the wifi adaptor. >>> >>> The highest possible speed of a gigabit connection is about 111 >>> megabytes per second. >>> >>> Naturally, I did some tests with a noncompressible 1 gigabyte long file >>> (fragment of some gzipped file exactly one GB long). >>> >>> My first test was to scp files from one computer on the switch to >>> another. Here, I was disappointed as the highest speed was only 22 >>> megabytes per second one way and 46 another way. About 20 and 40 >>> percent of maximum. >>> >>> Then I tried using HTTP to transfer the same file (both computers are >>> webservers). To my huge surprise, it made a world of difference and the >>> transfer speed was 111 or so megabytes per second. >>> >>> So, now I have a dilemma, I have a fast pipe, but scp is not fast >>> enough (given my CPU) to encrypt/decrypt so much data. >>> >>> I tried something else, which is doing wc -l on a NFS mounted drive >>> (same two computers). It was UNBELIEVABLY slow and the load average on >>> the NFS server shot WAY up. Transferring a 336 MB file took 157 >>> seconds, or about e megabytes per second (vs 111 mbps that I achieved >>> with HTTP). >> >> So, about 2.7 MB/s? :-) >> >> >>> So, the conclusion is, HTTP is fast (no wonder), SSH is "medium", and >>> NFS is "slow, very bad". >> >> I ran into a similar problem with NFS ages back. Turns out you can >> largely fix it by configuring NFS to increase the packet size. Been a >> few years since I did anything with NFS, though, so you'll have to look >> through the docs. I hear they use it in computer clusters, so it can't >> be slow in all cases. >How do you configure NFS to increase the packet size? Also are you >talking about NFS V4 or V3? when you mount it. Why didn't you just google for "nfs packet size"?