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Re: Slower transfers on XEN

"Marcin M. Jessa" <lists%yazzy.org@localhost> writes:

> On 03/17/2010 01:19 AM, Greg Troxel wrote:
>> "Marcin M. Jessa" <lists%yazzy.org@localhost> writes:
>>> I have an AMD64 server running NetBSD 5.0.2 with two 500Gb IDE drives.
>>> The drives are raided with RaidFrame and Raid 1. The FFS file systems
>>> are mounted with log option.
>>> Copying large files i noticed I get about 6-7 mbit/s when running Xen
>>> and about 10-11 when running GENERIC kernel and scping to the same
>>> file system.
>>> I had to disable ACPI on this server as well.
>>> Any idea why there is this dicrease in performance ?
>> My experience was
>>   RAID1 (raidframe) for dom0 fs
>>   UFS2 fs for backing files
>>   files created with dd (zero-filled, non-sparse)
>> I remember dimly
>>   70 MB/s read from raw raid device
>>   ~10% less read from file on dom0
>>   ~10% less than that read from 'raw device' on domU (rxbd0d)
>> so your 6-7 vs 10-11 seems like too much.  try the above 3 tests and
>> post the real numbers.
> Disabling ACPI and APIC in kernel improved transfer speed over ftp and
> scp with 70-80%.
> Why is this happening ?

You didn't post your results; people can't help without the facts.  I
would make all three measurements in both cases (stock kernel, and

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