On Wed, Jun 21, 2006 at 10:24:32AM -0400, Sinha_Himanshu@xxxxxxx wrote: > I misspoke earlier - our data is from a RHEL 4U1 system - 2.6.9 kernel. > We will try RHEL 4U3 soon. That will give us a later kernel. You need to go to 2.6.17 to get the performance enhancements I was talking about, and 2.6.17 is very new, released less than a week ago. I would compile that kernel myself for the testing. Best regards keld > Thanks > Himanshu > > -----Original Message----- > From: Keld Jørn Simonsen [mailto:keld@xxxxxxxx] > Sent: Wednesday, June 21, 2006 10:12 AM > To: Sinha, Himanshu > Cc: ext3-users@xxxxxxxxxx > Subject: Re: Limited write bandwidth from ext3 > > On Mon, Jun 19, 2006 at 02:18:12PM -0400, Sinha_Himanshu@xxxxxxx wrote: > > We are running a benchmark that does single threaded 512 KB writes to a > > LUN on a CLARiiON storage array. The dual Xeon host (Dell 2650) with 4 > > GB of memory runs RHEL 4U3 > > > > We measured the write bandwidth for writes to the block device > > corresponding to the lun (e.g. /dev/sdb), a file in an ext2 filesystem > > and to a file in an ext3 file system. > > Write b/w for 512 KB writes > > Block device 312 MBps > > Ext2 file 247 MBps > > Ext3 file 130 MBps > > > > We are looking for ways to improve the ext3 file write bandwidth. > > > > Tracing of I/Os at the storage array shows that in the case of ext3 > > experiment, the workload does not keep the lun busy enough. Every 5 > > seconds there is an increase in I/O activity that lasts for 2-3 seconds. > > The lun then has very low activity for 2-3 seconds. It appears that the > > buffers at the host are flushed every 5 seconds and the flushing takes > > 2-3 seconds. To maximize write bandwidth, we would like to be in a > > situation where the buffers are flushed continuously to keep the lun > > constanly busy. > > That is what we see in the case of the ext2 file. > > > > In the case of ext2 we also see the host do quite a few ver large writes > > (up to 7784 KB). > > Hmm, is the new kernel 2.6.17 addressing such issues? > I understand that the new multibuffered implementation of ext3 > may enhance the performance considerably. > > What kernel did you benchmark on? > > best regards > keld > > _______________________________________________ > > Ext3-users@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/ext3-users _______________________________________________ Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
