Hi Robert,

sounds great. Testing should be no problem, i’m able to update my platform 
image or change the QEMU binary.

Thanks
Kilian




Am 06.04.16, 16:49 schrieb "Robert Mustacchi" <[email protected]>:

>On 4/6/16 0:05 , Kilian Ries wrote:
>> -----------------  lwp# 85 / thread# 85  --------------------
>> 
>>  ffffdf7fff29f0ea _lwp_kill () + a
>> 
>>  ffffdf7fff2338f0 raise (6) + 20
>> 
>>  ffffdf7fff20db78 abort () + 98
>> 
>>  000000000054b172 qemu_oom_check (0) + 49
>> 
>>  000000000054b1ab qemu_memalign (200, 7e0000) + 33
>> 
>>  0000000000508a5d qemu_blockalign (f9dc70, 7e0000) + 4f
>> 
>>  000000000050c485 handle_aiocb_rw (9c51b5570) + c2
>> 
>>  000000000050c770 aio_thread (0) + 166
>> 
>>  ffffdf7fff297b5a _thrp_setup (ffffdf7fff079240) + 8a
>> 
>>  ffffdf7fff297e70 _lwp_start ()
> 
> So based on this thread I think I have an idea of what's happening and
> an idea of how to solve it.
> 
> Originally we didn't have preadv / pwritev in illumos and then when we
> initially added it, the amount of IOVECS we used was variable and QEMU
> didn't really respect IOVEC_MAX. Now, this matters because what QEMU
> appears to be doing here is saying because it has an I/O vector that it
> can't send, it's going to go ahead and try to basically allocate a large
> amount of memory to make it all one contiguous amount that it can send.
> 
> So, in this case I think what we can do is actually release the preadv /
> pwritev restrictions that came into place originally. This has the
> advantage that it should reduce the burden of memory allocation on qemu
> and thus speed up a bit of the I/O processing.
> 
> If I were able to produce a platform or a QEMU binary to test this
> against, would you be in a position to run this again, given that it
> seems to reproduce fairly frequently for you? It might be a couple days
> before I could get around to that.
> 
> Robert
> 


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