linux-kernel - Re: Question Regarding ERMS memcpy

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Date:   Sun, 5 Mar 2017 23:28:22 -0800
From:   "H. Peter Anvin" <hpa@...or.com>
To:     Logan Gunthorpe <logang@...tatee.com>,
        Borislav Petkov <bp@...e.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Tony Luck <tony.luck@...el.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Question Regarding ERMS memcpy

On 03/05/17 23:01, Logan Gunthorpe wrote:
> 
> On 05/03/17 12:54 PM, Borislav Petkov wrote:
>> Logan, wanna give that a try, see if it takes care of your issue?
> 
> Well honestly my issue was solved by fixing my kernel config. I have no
> idea why I had optimize for size in there in the first place.
> 

Yes, to gcc "optimize for size" means exactly that... intended for cases
where saving storage (e.g. ROM) or code download time is paramount.

We have frequently asked them for an optimization option that is not
strictly byte-count-based but still tries to reduce cache footprint, but
it is a nontrivial project.

	-hpa