[Top] [All Lists]

Re: High latencies writing to a memory mapped file

To: "Kinzel, David" <David.Kinzel@xxxxxxxxxx>
Subject: Re: High latencies writing to a memory mapped file
From: Matthias Schniedermeyer <ms@xxxxxxx>
Date: Tue, 27 Jul 2010 23:02:04 +0200
Cc: xfs@xxxxxxxxxxx
In-reply-to: <F57F2AD357626644AF76410876025D75529604@xxxxxxxxxxxxxxxxxxx>
References: <20100722144706.GA2840@xxxxxxxxxxxxxxxxxxxxxxxxx> <20100727092452.GA23307@xxxxxxx> <4C4EDEFD.7000401@xxxxxxxxxxxxxxxxx> <20100727144914.GA29349@xxxxxxx> <F57F2AD357626644AF76410876025D75529604@xxxxxxxxxxxxxxxxxxx>
User-agent: Mutt/1.5.19 (2009-01-05)
On 27.07.2010 13:59, Kinzel, David wrote:
> >> Matthias Schniedermeyer put forth on 7/27/2010 4:24 AM:
> >> 
> >> > We have a linux-computer with samba to act as a fileserver 
> >for a few 
> >> > Windows-Clients and ever since kernel 2.6.26 (Never 
> >happend with 2.6.25) 
> >> > the server randomly "hangs" for a few seconds (Which is more of a 
> >> > problem that drives people crazy).
> >> 
> The server hangs, or the connections to samba do? I've found that samba

That's a question i actually hadn't though about. This certainly extends 
the circle of possible culprits a little. From the top of my mind thats 
the the NIC (Intel e100) and it's e100-driver and the (As Cheap as 
possible) 24-port 100MBit-Switch used to connect all computers. And last 
but not least the whole TCP/IP network-stack in the kernel.

This also differentiates "our" server to the mentioned "copy" which uses 
whichever GBit-NIC that was onboard (Something from Realtek AFAIR) to 
the a tree of even cheaper 5 and 8 port switches, not to mention 

> is given a ridiculously low IO priority so that any IO on the server
> will pretty much cause it to stall -- be it updating locate, a backup
> job, etc. 

Whatever the culprit is, in our case it's something that changed between 
2.6.25 and 2.6.26, before 2.6.26 we were happy with whatever was current 
for years. (System is running a reguarly updated Debian SID for at least 
6-7 years)

And the most irritating things is the "a reboot fixes it". When the 
problem reared it's head, you can restart samba, drop all caches, 
umount/decompose the RAID and whatnot, the problem immediatly reappears
after you get back to working conditions.

Bis denn

Real Programmers consider "what you see is what you get" to be just as 
bad a concept in Text Editors as it is in women. No, the Real Programmer
wants a "you asked for it, you got it" text editor -- complicated, 
cryptic, powerful, unforgiving, dangerous.

<Prev in Thread] Current Thread [Next in Thread>