Re: [RFC PATCH] makefile: add debug option to enable function aligned on 32 bytes

[Feng Tang]

On Thu, Jul 23, 2020 at 05:57:04PM -0700, Andrew Morton wrote:
> On Thu, 23 Jul 2020 14:29:33 +0800 Feng Tang <feng.tang@xxxxxxxxx> wrote:
> 
> > > > gcc has an option '-falign-functions=n' to force text aligned, and with
> > > > that option enabled, some of those performance changes will be gone,
> > > > like [1][2][3].
> > > > 
> > > > Add this option so that developers and 0day can easily find performance
> > > > bump caused by text alignment change,
> > > 
> > > Would they use it this way, or would they simply always enable the
> > > option to reduce the variability?
> > 
> > I may mis-understood it in my last reply. If you are asking about how
> > will developers and 0day use this option, for 0day, I've talked with
> > 0day folks, they may just enable it by default, as 0day cares more about
> > the performance delta caused by a commit (Adding Philip and Rong from
> > 0day).
> 
> OK, thanks, I suspected as much.
> 
> The patch is so simple and probably-will-work, I guess we toss it in
> there and see.

Thanks!

> However it would be good if the 0day people could use it for a while
> and then provide some feedback on whether it is actually proving
> useful.  If not, we get to remove some stuff.

Yes, 0day is a good user to try this.

Thanks,
Feng