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[60.242.147.73]) by smtp.gmail.com with ESMTPSA id l126sm2665004pfl.16.2021.06.04.17.17.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Jun 2021 17:17:56 -0700 (PDT) Date: Sat, 05 Jun 2021 10:17:50 +1000 From: Nicholas Piggin Subject: Re: [PATCH v3 0/4] shoot lazy tlbs To: Andrew Morton , Andy Lutomirski Cc: Anton Blanchard , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Randy Dunlap References: <20210601062303.3932513-1-npiggin@gmail.com> <603ffd67-3638-4c47-8067-c1bdfdf65f1b@kernel.org> <991660c3-c2bf-c303-a55c-7454f0cc45f7@kernel.org> In-Reply-To: <991660c3-c2bf-c303-a55c-7454f0cc45f7@kernel.org> MIME-Version: 1.0 Message-Id: <1622851909.wxi3vcx3m8.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org Excerpts from Andy Lutomirski's message of June 5, 2021 3:05 am: > On 6/4/21 9:54 AM, Andy Lutomirski wrote: >> On 5/31/21 11:22 PM, Nicholas Piggin wrote: >>> There haven't been objections to the series since last posting, this >>> is just a rebase and tidies up a few comments minor patch rearranging. >>> >>=20 >> I continue to object to having too many modes. I like my more generic >> improvements better. Let me try to find some time to email again. >>=20 >=20 > Specifically, this: >=20 > https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h= =3Dx86/mm That's worse than what powerpc does with the shoot lazies code so=20 we wouldn't use it anyway. The fact is mm-cpumask and lazy mm is very architecture specific, so I=20 don't really see that another "mode" is such a problem, it's for the=20 most part "this is what powerpc does" -> "this is what powerpc does". The only mode in the context switch is just "take a ref on the lazy mm" or "don't take a ref". Surely that's not too onerous to add!? Actually the bigger part of it is actually the no-lazy mmu mode which is not yet used, I thought it was a neat little demonstrator of how code works with/without lazy but I will get rid of that for submission. > I, or someone, needs to dust off my membarrier series before any of > these kinds of changes get made. The barrier situation in the scheduler > is too confusing otherwise. >=20 I disagree, I've disentangled the changes from membarrier stuff now,=20 they can be done concurrently. Thanks, Nick