Hi! I wonder whether anybody did try to play with network tuning parameters related to iSCSI. Candidates might be "net.core.?mem*". I've seen these setting for a database server, but I don't know what the intention of these actually is:
net.core.rmem_default = 262144 net.core.wmem_default = 262144 net.core.rmem_max = 4194304 net.core.wmem_max = 1048576 Regards, Ulrich >>> Heinrich Langos <[email protected]> schrieb am 09.09.2011 um 09:02 in Nachricht <[email protected]>: > On Thu, Sep 08, 2011 at 09:25:29PM -0500, Mike Christie wrote: > > On 09/08/2011 09:23 PM, Mike Christie wrote: > > > On 09/08/2011 04:36 PM, Mike Christie wrote: > > >> On 09/08/2011 02:06 AM, Heinrich Langos wrote: > > >>> Hi htere, > > >>> > > >>> I am using the open-iscsi initiator to access a storage back end for > > >>> my Xen based virtualization infrastructure. > > >>> Since The current 3.0.x Linux kernel finally has everything that I > > >>> need to run the host system (Dom0) without any additional patches I > > >>> thought I'd give it a try and see if I can replace the 2.6.32 hosts > > >>> that cause a lot of trouble when mixing Xen + iSCSI + multipath. > > >>> > > >>> This is raw "dd" throughput for reading ~30GB from an iSCSI storage > > >>> via a dedicated 1GB Ethernet link. > > >>> > > >>> 2.6.32 : 102 MB/s > > >>> 2.6.38 : 100 MB/s > > >>> 2.6.39 : 44 MB/s > > >>> 3.0.1 : 43 MB/s > > >>> > > >> > > >> I can replicate this now. For some reason I only see it with 1 gig. I > > >> think my 10 gig setups that I have been testing with are limited by > > >> something else. > > >> > > >> Doing git bisect now to track down the change that caused the problem. > > >> > > First of all thank you very much for taking a look at it. I was wondering if > I was doing something strange since I havn't seen anybody report anything > similar and 2.6.39 is out a while now. But I guess iSCSI users tend to be > coporate users and they don't junp on every new kernel version. > > > > I did not find anything really major in the iscsi code. But I did notice > > > that if I just disable iptables throughput goes from about 5 MB/s back > > > up to 85 MB/s. > > > > > > If you disable iptables do you see something similar. > > > > > > > I also noticed that in 2.6.38 throughput would almost immediately start > > at 80-90 MB/s, but with 2.6.39 it takes a while (maybe 10 seconds > > sometimes) to ramp up. > > I've noticed the oposite. Throughput starts high and goes down to the > numbers reported after about 10 gigabyte. I've noticed with all the kernels > I've tested but that is proably a result of the crude way of measuring > that I use. > > I run 'dd if=/dev/disk/by-path/... of=/dev/null bs=1024k &' > and 'while kill -USR1 <dd-pid> ; do sleep 2 ; done' . > Therefore I usually don't get to see the thoughput during the first couple > of seconds. I'm open to suggestions to improve this. > > I took a look at ip_tables with kernel 3.0.1 (I'll check out the other > versions later today.) > If I rmmod iptable_filter ip_tables and x_tables the performance starts > out higher (over 80 instead of over 60) and drops down to around 63 > instead of 43. Still not back up in the region it was before. > > cheers > -henrik -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/open-iscsi?hl=en.
