Re: mm/cma.c: High latency for cma allocation

[Michal Hocko]

On Mon 18-03-19 12:58:28, Pankaj Suryawanshi wrote:
> Hello,
> 
> I am facing issue of high latency in CMA allocation of large size buffer.
> 
> I am frequently allocating/deallocation CMA memory, latency of allocation is very high.
> 
> Below are the stat for allocation/deallocation latency issue.
> 
> (390100 kB),  latency 29997 us
> (390100 kB),  latency 22957 us
> (390100 kB),  latency 25735 us
> (390100 kB),  latency 12736 us
> (390100 kB),  latency 26009 us
> (390100 kB),  latency 18058 us
> (390100 kB),  latency 27997 us
> (16 kB), latency 560 us
> (256 kB), latency 280 us
> (4 kB), latency 311 us
> 
> I am using kernel 4.14.65 with android pie(9.0).
> 
> Is there any workaround or solution for this(cma_alloc latency) issue ?

Do you have any more detailed information on where the time is spent?
E.g. migration tracepoints?

-- 
Michal Hocko
SUSE Labs