On 10/15/2012 05:34 PM, Scott Marlowe wrote:
> On Mon, Oct 15, 2012 at 9:28 AM, Claudio Freire <klaussfreire(at)gmail(dot)com> wrote:
>> On Mon, Oct 15, 2012 at 12:24 PM, Andrea Suisani <sickpig(at)opinioni(dot)net> wrote:
>>> sure you're right.
>>>
>>> It's just that my bet was on a higher throughput
>>> when HT was isabled from the BIOS (as you stated
>>> previously in this thread).
>>
>> Yes, mine too. It's bizarre. If I were you, I'd look into it more
>> deeply. It may be a flaw in your test methodology (maybe you disabled
>> the wrong cores?). If not, it would be good to know why the extra TPS
>> to replicate elsewhere.
>
> I'd recommend more synthetic benchmarks when trying to compare systems
> like this. bonnie++,
you were right. bonnie++ (-f -n 0 -c 4) show that there's very little (if any)
difference in terms of sequential input whether or not cache is enabled on the
RAID1 (SAS 15K, sdb).
I've run 2 bonnie++ test with both cache enabled and disabled and what I get
(see attachments for more details) it's a 400MB/s sequential input (cache) vs
390MBs (nocache).
I dunno why but I would have expected a higher delta (due to the 512MB cache)
not a mere 10MB/s, but this is only based on my gut feeling.
I've also tried to test RAID1 array where the OS is installed (2 SATA 7.2Krpm, sda)
just to verify if cache effect is comparable with the one I get from SAS disks.
Well it seems that there's no cache effects or if it's is there is so small as to be
confused with the noise.
Both array are configured with this params
Read Policy : Adaptive Read Ahead
Write Policy : Write Back
Stripe Element Size : 64 KB
Disk Cache Policy : Disabled
those tests are performed with HT disable from the BIOS, but without
using noht kernel boot param. the scheduler for sdb was setted to deadline
while the default cfq for sda.
> the memory stream test that Greg Smith was
> working on, and so on.
this one https://github.com/gregs1104/stream-scaling, right?
I've executed the test with HT enabled, HT disabled from the BIOS
and HT disable using sys interface. Attached 3 graphs and related
text files
> Get an idea what core differences the machines
> display under such testing.
I'm trying... hard :)
Andrea
