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

12/09/2007, 14h52

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?

12/09/2007, 14h52	#3
General Schvantzkoph Messages: n/a Hébergeur:	Re: Gigabit Ethernet, and Linux -- first observations 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?