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Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1ti9tE-00000004EIe-0lYC; Wed, 12 Feb 2025 10:22:44 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id EB30E300318; Wed, 12 Feb 2025 11:22:42 +0100 (CET) Date: Wed, 12 Feb 2025 11:22:42 +0100 From: Peter Zijlstra To: Rik van Riel Cc: x86@kernel.org, linux-kernel@vger.kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, zhengqi.arch@bytedance.com, nadav.amit@gmail.com, thomas.lendacky@amd.com, kernel-team@meta.com, linux-mm@kvack.org, akpm@linux-foundation.org, jackmanb@google.com, jannh@google.com, mhklinux@outlook.com, andrew.cooper3@citrix.com, Manali Shukla Subject: Re: [PATCH v10 09/12] x86/mm: enable broadcast TLB invalidation for multi-threaded processes Message-ID: <20250212102242.GB24784@noisy.programming.kicks-ass.net> References: <20250211210823.242681-1-riel@surriel.com> <20250211210823.242681-10-riel@surriel.com> <20250212095438.GC19118@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250212095438.GC19118@noisy.programming.kicks-ass.net> X-Rspamd-Queue-Id: CAC48C0006 X-Stat-Signature: awggnhc1biao1pr7tq89o7yi5o5rghrh X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1739355771-831304 X-HE-Meta: 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 CC7GtWb5 2Qap4H95aeAIABDKvSkMk1E/i5iZM235YiXrdSSAF2uIRrB0mwFMcpEGReAheWinttuPKFtDwNlAKqLB/l9NJV09sns9w7wDn6AOaclhYcTgetRlTaGPewCaXxXJQF4zAtaZBFMZBl5BtRtdcsdf+kyJhn8hxhyKBzzBVQdo0iFB6p4OazNEephAtXVN5/q4JcEZ0XhGlH9YPE4393RHcKbW1XuOU+y5qtIuTKtTOnt2UdUrI073jANWQFhTtPc9NpjOa49NVOYdn0Ac= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Feb 12, 2025 at 10:54:38AM +0100, Peter Zijlstra wrote: > On Tue, Feb 11, 2025 at 04:08:04PM -0500, Rik van Riel wrote: > > > +static void broadcast_tlb_flush(struct flush_tlb_info *info) > > +{ > > + bool pmd = info->stride_shift == PMD_SHIFT; > > + unsigned long maxnr = invlpgb_count_max; > > + unsigned long asid = info->mm->context.global_asid; > > + unsigned long addr = info->start; > > + unsigned long nr; > > + > > + /* Flushing multiple pages at once is not supported with 1GB pages. */ > > + if (info->stride_shift > PMD_SHIFT) > > + maxnr = 1; > > How does this work? > > Normally, if we get a 1GB range, we'll iterate on the stride and INVLPG > each one (just like any other stride). > > Should you not instead either force the stride down to PMD level or > force a full flush? Oh, n/m, I think I see.