[PATCH v4 13/13] riscv: Add qspinlock support

[Alexandre Ghiti]

Hi drew,

On Wed, Aug 21, 2024 at 2:18 PM Andrew Jones <ajones at ventanamicro.com> wrote:
>
> On Sat, Aug 17, 2024 at 01:08:34PM GMT, Guo Ren wrote:
> ...
> > > So I have just checked the size of the jump table section:
> > >
> > > * defconfig:
> > >
> > > - ticket: 26928 bytes
> > > - combo: 28320 bytes
> > >
> > > So that's a ~5% increase.
> > >
> > > * ubuntu config
> > >
> > > - ticket: 107840 bytes
> > > - combo: 174752 bytes
> > >
> > > And that's a ~62% increase.
> > The size of the jump table section has increased from 5% to 62%. I
> > think some configuration triggers the jump table's debug code. If it's
> > not a debugging configuration, that's a bug of the Ubuntu config.
>
> And I just remembered we wanted to check with CONFIG_CC_OPTIMIZE_FOR_SIZE

Here we go!

The size of the jump table section:

* defconfig:

- ticket: 12176 bytes
- combo: 13168 bytes

So that's a ~8% increase.

* ubuntu config

- ticket:   73920 bytes
- combo: 84656 bytes

And that's a ~14% increase.

This is the ELF size difference between ticket and combo spinlocks:

* ticket:   695906872 bytes
* combo: 697558496 bytes

So that's an increase of ~0.23% on the ELF.

And the .text section size:

* ticket:   10322820 bytes
* combo: 10332136 bytes

And that's a ~0.09% increase!

So that's even better :)

Thanks for asking!

Alex

>
> Thanks,
> drew
>
> >
> > >
> > > This is the ELF size difference between ticket and combo spinlocks:
> > >
> > > * ticket: 776915592 bytes
> > > * combo: 786958968 bytes
> > >
> > > So that's an increase of ~1.3% on the ELF.
> > >
> > > And the .text section size:
> > >
> > > * ticket: 12290960 bytes
> > > * combo: 12366644 bytes
> > >
> > > And that's a ~0.6% increase!
> > >
> > > Finally, I'd say the impact is very limited :)
> > >
> > > Thanks,
> > >
> > > Alex
> > >
> > >