linux-kernel - Re: [PATCH 084/208] x86/fpu: Rename xsave.header::xstate

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Message-ID: <20150507105859.GH6859@pd.tnic>
Date:	Thu, 7 May 2015 12:59:00 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Dave Hansen <dave.hansen@...ux.intel.com>
Cc:	Ingo Molnar <mingo2.kernel.org@...il.com>,
	linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@...capital.net>,
	Fenghua Yu <fenghua.yu@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 084/208] x86/fpu: Rename xsave.header::xstate_bv to
 'xfeatures'

On Wed, May 06, 2015 at 11:27:47AM -0700, Dave Hansen wrote:
> But we'd need to get to a point where we are calling 'xsaves' with a
> Requested Feature BitMask (aka RFBM[]) that had holes in it.  As it
> stands today, we always call it with RFBM=-1 and so we always have
> XCOMP_BV = XCR0.
> 
> We'd need to determine which fields are in the init state before we do
> an xsaves.

Btw, do we have any perf data as to the improvement the compacted
variant brings?

I mean, it means a bunch of jumping through hoops in SW but is it worth
it?

Thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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