mark delfman wrote:
Hi... in recent tests we are seeing a 50% drop in performance from
XFS>MD on a 2.6.30 kernel (compared to a 2.6.28 kernel)
I can very loosely (based on very early testing and slightly different
hardware) agree.
A couple of 2.6.27.19-78.2.30.fc9.x86_64 machines - 8GB RAM LSI SAS
controller and 16 x WD RE3 750GB SATA md RAID6.
With stripe cache set to 16384, I see dd writes of 590MB/s.
Started testing a similar machine yesterday - 12GB RAM LSI SAS
controller and 16 x WD RE3 1TB SATA md RAID6.
With stripe cache set to 16384, I see dd writes of around 290MB/s and
when bumped up to 32768 (the maximum), it increases to 407MB.
Read performance is about the same as the older system - around 960MB/s.
Both systems are using XFS with an external journal.
As I say, early days - I've not compared scheduler etc. settings between
kernels, but somewhatr disappointing.
Regards,
Richard
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