Hi Sampad,

To literally answer the clone error part: this happens when your
application needs multiple thread contexts to run.  The failure happens
when -n 1 is used because the simulator doesn't have enough thread contexts
to fulfill what the application needs.

Of course, the next logical question is why ROCm needs 2 thread contexts.
I haven't looked at this specific behavior in several years, but when I dug
into this in ~2018, I remember this happening because the ROCm stack was
spawning a thread to check on some details about the system (e.g., it was
checking if the HCC version was at least version X, because starting with
that version, the HCC behavior was different).  If you are interested in
finding the exact call that does this, you can build a debug version of the
ROCm stack and step through the ROCm stack with gdb while the simulator is
running.  Eventually you'll get to the instruction in the ROCm stack that
is doing checks like the one I described above, and you could potentially
remove that call and return true/false instead as appropriate for the check
it's doing.  This is what I did previously, although I don't think that
ROCm patch has been merged into develop or the AMD staging branch yet
(although like some of the other ROCm patches, it would actually need to be
placed elsewhere like gem5-resources, not directly in the gem5 repo, since
it doesn't affect gem5 code).

Alternatively, you can just run with -n 2, as you've found already.  It
should have very minimal impact on running the application.

Matt

On Fri, Aug 7, 2020 at 11:46 PM Sampad Mohapatra via gem5-users <
[email protected]> wrote:

> Hi All,
>
> Why does the GCN3 model require at least 2 CPUs ?
> Every time I use a single CPU, gem5 crashes with the following error:
> *fatal: clone: no spare thread context in system*
>
> In contrast, I was able to run the HSAIL model with a single CPU.
>
> Thank You,
> Sampad Mohapatra
>
>
> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon>
>  Virus-free.
> www.avast.com
> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link>
> <#m_4482362651241885149_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
> _______________________________________________
> gem5-users mailing list -- [email protected]
> To unsubscribe send an email to [email protected]
> %(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s
_______________________________________________
gem5-users mailing list -- [email protected]
To unsubscribe send an email to [email protected]
%(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s

Reply via email to