linux-kernel - Re: [PATCH 06/12] x86/mm: use INVLPGB for kernel TLB flushes

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Message-ID: <65c9fa727810df986c4e576799af430c35b9d40e.camel@surriel.com>
Date: Fri, 10 Jan 2025 11:36:29 -0500
From: Rik van Riel <riel@...riel.com>
To: Dave Hansen <dave.hansen@...el.com>, Nadav Amit <nadav.amit@...il.com>
Cc: the arch/x86 maintainers <x86@...nel.org>, Linux Kernel Mailing List	
 <linux-kernel@...r.kernel.org>, kernel-team@...a.com, Dave Hansen	
 <dave.hansen@...ux.intel.com>, luto@...nel.org, peterz@...radead.org,
 Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, "H. Peter Anvin"	 <hpa@...or.com>, Andrew
 Morton <akpm@...ux-foundation.org>, 	zhengqi.arch@...edance.com, "open
 list:MEMORY MANAGEMENT" <linux-mm@...ck.org>
Subject: Re: [PATCH 06/12] x86/mm: use INVLPGB for kernel TLB flushes

On Fri, 2025-01-10 at 08:29 -0800, Dave Hansen wrote:
> >  about.
> 
> IIRC, the "big" invalidation modes are pretty cheap to execute. Most
> of
> the cost comes from the TLB refill, not the flush itself.
> 
> But there's no substitute for actually measuring it. There's some
> wonky
> stuff out there. The last time Andy L. went and looked at it, there
> were
> oddities like INVPCID's "Individual-address invalidation" and INVLPG
> having surprisingly different performance.
> 
Agreed on all points.

If you guys don't mind, I'm going to keep this on the
back burner, while I work my way through all the
suggested code cleanups and improvements first.

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