Re: [Scst-devel] SRP transfer size

[Nikolai K. <nik...@gm...>]

Sorry, I set cmd_sg_entries to 255 (maximum value) to get 512KB transfers.

On Mon, May 28, 2012 at 5:21 PM, Nikolai Kopanygin
<nik...@gm...> wrote:
> Thanks, Bart, it works.
>
> On a Linux intiator, I set in ib_srp module cmd_sg_tablesize to 512,
> and the transfer size is 512KB now.
>
> Nikolai.
>
> On Mon, May 28, 2012 at 3:34 PM, Bart Van Assche <bva...@ac...> wrote:
>> On 05/28/12 10:26, Nikolai Kopanygin wrote:
>>
>>> I have a problem with the SRPT driver. When I write to the IB target
>>> with large blocks (128KB and greater), those get split into pieces not
>>> greater than 68KB. This happens no matter Windows or Linux initiator
>>> I use. Can anyone give me advice how to change this behavior?
>>
>>
>> ib_srpt definitely supports transfer sizes above 68 KB. Are you perhaps
>> using asynchronous (buffered) I/O ? Also, when using a Linux initiator,
>> has the cmd_sg_entries kernel module parameter been set to a large
>> enough value ? If you want to verify whether a Linux initiator has been
>> configured correctly, you can use the script "scripts/blockdev-perftest"
>> in the SCST tree. With the option -d it issues reads and write requests
>> for a range of block sizes. On the target you can check the actual
>> transfer sizes in /sys/kernel/scst_tgt/sgv/sgv/stats.
>>
>> Bart.