Re: [Qemu-devel] [V2 0/25] Async threading for VirtFS using glib threads & coroutines.

[Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>]

On 05/18/2011 03:39 AM, Stefan Hajnoczi wrote:
> On Tue, May 17, 2011 at 8:43 PM, Venkateswararao Jujjuri (JV)
> <jvrao@linux.vnet.ibm.com>  wrote:
>
> I sent comments on individual patches.  This is turning out nice, many
> of the PDU handlers are now straight-line code that can be followed
> easily.
>
Thanks. Yeah it is coming out nice. :-)

>> o Redesigned to use bh as per Stefan's suggestion.
>>   This made the code very simple but is little less performant compared to V1.
>>   Anthony suggested to go-in with cleaner code and design (This version) and
>>   deal with the performance later.
>>   Just to put in perspective:
>>   Sequential Writes of creating 1GB files using ffsb
>>   o Write size 8k
>>   With bh: 66.9MB/sec
>>   Without bh (marshalling routines): 74.9 MB/sec
>>
>>   o Write size 128k
>>   With bh: 117MB/sec
>>   Without bh (marshalling routines): 122MB/sec
> It would be interesting to hack in a post-yield callback which is
> invoked after yield transfers control back to the calling coroutine.
> This avoids setting up a BH and notifying the iothread to invoke it.
> I'm just suggesting this as an experiment to see if the BH mechanism
> causes the performance degradation, not as a real solution.
>
Correct, plan is to get the functionality in first and then handle this 
area.

Thanks,
JV

> Stefan
>