From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f199.google.com (mail-qk0-f199.google.com [209.85.220.199]) by kanga.kvack.org (Postfix) with ESMTP id 9DD8B6B40BE for ; Mon, 27 Aug 2018 09:37:08 -0400 (EDT) Received: by mail-qk0-f199.google.com with SMTP id v65-v6so14751530qka.23 for ; Mon, 27 Aug 2018 06:37:08 -0700 (PDT) Received: from shelob.surriel.com (shelob.surriel.com. [96.67.55.147]) by mx.google.com with ESMTPS id e186-v6si3473075qkf.291.2018.08.27.06.37.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Aug 2018 06:37:06 -0700 (PDT) Message-ID: <405ba257e730d4f0ad9007490e7ac47cc343c720.camel@surriel.com> Subject: Re: [PATCH 3/4] mm/tlb, x86/mm: Support invalidating TLB caches for RCU_TABLE_FREE From: Rik van Riel Date: Mon, 27 Aug 2018 09:36:50 -0400 In-Reply-To: <20180827180458.4af9b2ac@roar.ozlabs.ibm.com> References: <20180822155527.GF24124@hirez.programming.kicks-ass.net> <20180823134525.5f12b0d3@roar.ozlabs.ibm.com> <776104d4c8e4fc680004d69e3a4c2594b638b6d1.camel@au1.ibm.com> <20180823133958.GA1496@brain-police> <20180824084717.GK24124@hirez.programming.kicks-ass.net> <20180824113214.GK24142@hirez.programming.kicks-ass.net> <20180824113953.GL24142@hirez.programming.kicks-ass.net> <20180827150008.13bce08f@roar.ozlabs.ibm.com> <20180827074701.GW24124@hirez.programming.kicks-ass.net> <20180827180458.4af9b2ac@roar.ozlabs.ibm.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-CjA5zgmeZESrmuJDh+sg" Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Nicholas Piggin , Peter Zijlstra Cc: Will Deacon , Linus Torvalds , Benjamin Herrenschmidt , Andrew Lutomirski , the arch/x86 maintainers , Borislav Petkov , Jann Horn , Adin Scannell , Dave Hansen , Linux Kernel Mailing List , linux-mm , David Miller , Martin Schwidefsky , Michael Ellerman --=-CjA5zgmeZESrmuJDh+sg Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2018-08-27 at 18:04 +1000, Nicholas Piggin wrote: > It could do that. It requires a tlbie that matches the page size, > so it means 3 sizes. I think possibly even that would be better > than current code, but we could do better if we had a few specific > fields in there. Would it cause a noticeable overhead to keep track of which page sizes were removed, and to simply flush the whole TLB in the (unlikely?) event that multiple page sizes were removed in the same munmap? Once the unmap is so large that multiple page sizes were covered, you may already be looking at so many individual flush operations that a full flush might be faster. Is there a point on PPC where simply flushing the whole TLB, and having other things be reloaded later, is faster than flushing every individual page mapping that got unmapped? --=20 All Rights Reversed. --=-CjA5zgmeZESrmuJDh+sg Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEKR73pCCtJ5Xj3yADznnekoTE3oMFAluD/nIACgkQznnekoTE 3oPuoAgAgYYUxuaSllsIwNGF9TwctKvO64J9eWJukeqnJu357LE/C4ku0xwCXmhV 51RiEMNOpnTEQ/DWfPXjnCzY/Uah4nBXPTIwBjHCKC57tJGcIt1V9PsvnyRgtBDR hf05gT/oO+Cuj4KAATK5gjfUpuNt3w/xg3Gsoxqv7fRcDH5czAu74JpSY1U1IrGP Ck2UVC9AARlmeAhnonEnBw+dFkZsMgIvIZyvVSY9ZL01r3zdXuieEzeeDRV8t4IG w0ccBoWSO07Si+zZNrvk7Bo3SpHolzZbov8SLGqi1jnNplO25xw/Fkx2kVgMMXmB aTdmEoWMISm8Gr7LshmkZ1RhAVQWrA== =vAtB -----END PGP SIGNATURE----- --=-CjA5zgmeZESrmuJDh+sg--