Re: [PATCH v6] eal: allow worker lcore stacks to be allocated from hugepage memory

[Don Wallwork <donw@xsightlabs.com>]

On 6/21/2022 10:42 AM, Thomas Monjalon wrote:
> 21/06/2022 14:31, Don Wallwork:
>> On 6/21/2022 6:37 AM, Thomas Monjalon wrote:
>>> 20/06/2022 10:35, David Marchand:
>>>> On Tue, May 24, 2022 at 9:52 PM Don Wallwork <donw@xsightlabs.com> wrote:
>>>>> Add support for using hugepages for worker lcore stack memory.  The
>>>>> intent is to improve performance by reducing stack memory related TLB
>>>>> misses and also by using memory local to the NUMA node of each lcore.
>>>>> EAL option '--huge-worker-stack [stack-size-in-kbytes]' is added to allow
>>>>> the feature to be enabled at runtime.  If the size is not specified,
>>>>> the system pthread stack size will be used.
>>>> - About the name of the option... I don't have a better name.
>>>>
>>>> Just want to highlight, that what this patch does is use the DPDK
>>>> memory allocator for the stack memory.
>>>> It happens that DPDK memory allocator is primarily used with
>>>> hugepages, but this is not systematic for example with the "no-huge"
>>>> mode of the DPDK memory allocator.
>>>>
>>>> IOW, in this patch current form, you can still run as:
>>>>
>>>> # dpdk-testpmd -c 3 --no-huge --huge-worker-stack=16 -m 40 -- etc...
>>>>
>>>> Opinions?
>>> The name of the option should not include "huge".
>>> What about "--worker-stack" ?
>>> If disabled (equal zero), the workers should use the default stack memory.
>>>
>>>
>> Wouldn't that have the potential to create confusion?  The point of this
>> change is to allocate worker stacks from hugepages.  Removing huge
>> from the option name could give the impression that the command is
>> simply to control worker stack size.
> It means if we control the worker stack size with a DPDK option,
> DPDK memory will be used.
> But we cannot force hugepage with this option.
> Hugepage is not always available and it can be disabled in DPDK.

The command could be rejected if hugepages are not available.
That's not in the patch currently, but can be added.