[stgt] tgt reset on simple simulator

osishkin osishkin osishkin at gmail.com
Tue Jun 18 07:31:31 CEST 2013

Just in case anyone encounters this issue at some point - the problem
was a concurrency issue. When I call the request termination callback,
target_cmd_io_done accesses an internal list in tgt, which is at the
same time accessed by tgt threads. The access is not thread-safe. When
I accessed it in a protected manner using a mutex, the issue was

On Sun, Jun 16, 2013 at 1:06 PM, osishkin osishkin <osishkin at gmail.com> wrote:
> I'm pretty certain now that the problem is me not performing the
> requests in a sync manner.
> I wrote a mock code, in which on receipt I insert all r/w requests to
> a queue. A secondary thread simply polls in small intervals (50us) on
> the queue, dequeues all pneding requests and writes data to RAM.
> This is the most basic async setup possible, and it still doesn't pass
> my file system benchmark successfully. I should note that when simply
> performing the write to RAM and returning (without the extra queuing
> phase) the benchmark is successful.
> I see that there is bs_aio.c which does a very similar thing to what I
> do, but using polling on a pipe. I'm not familiar with this method,
> but it doesnt sound inherently different from what I do with threads
> and mutexes.
> So I wonder why the behavior changes so drastically between the two
> implementations.
> I'd appreciate your help.
> Thank you
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