Re: Hard and soft lockups with FIO and LTP runs on a large system

[Bharata B Rao <bharata@amd.com>]

On 17-Jul-24 4:45 PM, Hillf Danton wrote:
> On Wed, 17 Jul 2024 16:20:04 +0530 Bharata B Rao <bharata@amd.com>
>> On 17-Jul-24 3:07 PM, Vlastimil Babka wrote:
>>>
>>> It seems weird to me to see anything that would require ZONE_DMA allocation
>>> on a modern system. Do you know where it comes from?
>>
>> We measured the lruvec spinlock start, end and hold
>> time(htime) using sched_clock(), along with a BUG() if the hold time was
>> more than 10s. The below case shows that lruvec spin lock was held for ~25s.
>>
> What is more unusual could be observed perhaps with your hardware config but
> with 386MiB RAM assigned to each node, the so called tight memory but not
> extremely tight.

Hardware config is this:

Dual socket  AMD EPYC 128 Core processor (256 cores, 512 threads)
Memory: 1.5 TB
10 NVME - 3.5TB each
available: 2 nodes (0-1)
node 0 cpus: 0-127,256-383
node 0 size: 773727 MB
node 1 cpus: 128-255,384-511
node 1 size: 773966 MB

But I don't quite follow what you are hinting at, can you please 
rephrase or be more verbose?

Regards,
Bharata.