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bh=i7R0serjdAd95/t2bcbDMvmqk9PuKfWQm9HVe5uYFlU=; b=ICHoW9E6IDEliSlqPAQ186Pit1ESPe++Q23Ty/56MQJ18783ff4rTHS8smkhV8kGBQhU3L Sba9Tk28GgyafPXjARMd5YP8aBLMiL1kRN62UZD7n9+kna78Fb5bSL2dDFhKlnZg7ty07m swzQO11FOK2AfzC0O843hT02TO57d2eQyb+ScHT0RvR/iDgmGv0KkmpHhATVtC9yvOeOKs y01UDqIDhMdxkkePQ6C0A4IZyPSe8GGQcsQ3IWv3iqAoMqlUf5pWHWp/93WdrJmTDqpxHO MKRrXKwmPsbgu+VsdgOE8pmc20j3rRThDthUoby23OGQ9YadQHRaNOjCZ5AaNQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1684265552; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=i7R0serjdAd95/t2bcbDMvmqk9PuKfWQm9HVe5uYFlU=; b=5uypkhwF3F6JvIFA79fz1JDY9g9sJqnc/kgLqihD/wKYR9wvq+dSSm1eVyrFm1zXmYQvFx g1gjZ5rPyjMyLKDw== To: Nadav Amit Cc: Uladzislau Rezki , "Russell King (Oracle)" , Andrew Morton , linux-mm , Christoph Hellwig , Lorenzo Stoakes , Peter Zijlstra , Baoquan He , John Ogness , linux-arm-kernel@lists.infradead.org, Mark Rutland , Marc Zyngier , x86@kernel.org Subject: Re: Excessive TLB flush ranges In-Reply-To: <7ED917BC-420F-47D4-8956-8984205A75F0@gmail.com> References: <87a5y5a6kj.ffs@tglx> <87353x9y3l.ffs@tglx> <87zg658fla.ffs@tglx> <87r0rg93z5.ffs@tglx> <87cz308y3s.ffs@tglx> <87y1lo7a0z.ffs@tglx> <87o7mk733x.ffs@tglx> <7ED917BC-420F-47D4-8956-8984205A75F0@gmail.com> Date: Tue, 16 May 2023 21:32:32 +0200 Message-ID: <87bkik6pin.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain X-Stat-Signature: 6tqefk8o84jszdrc9a9twh76tk1rjw1z X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 0ED7B40014 X-HE-Tag: 1684265554-414215 X-HE-Meta: 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 Ejl2nfUW ieLvxNmJfFBaovDfW3PScXyinZpAfopWkYPSvdjZ4a9xfWNCMNNjZPKZfoalnBVXJlHGB2J50gIJaX2TJ2yLE2rp5Jn8M2r6qfiFNxv8Rpoi6OpKLObQPnfcOqw== 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: On Tue, May 16 2023 at 10:56, Nadav Amit wrote: >> On May 16, 2023, at 7:38 AM, Thomas Gleixner wrote: >> >> There is a world outside of x86, but even on x86 it's borderline silly >> to take the whole TLB out when you can flush 3 TLB entries one by one >> with exactly the same number of IPIs, i.e. _one_. No? > > I just want to re-raise points that were made in the past, including in > the discussion that I sent before and match my experience. > > Feel free to reject them, but I think you should not ignore them. I'm not ignoring them and I'm well aware of these issues. No need to repeat them over and over. I'm old but not senile yet. It might turn out that it's not the proper solution for x86, but the generic vmalloc code as of today is written with an x86 centric view. That actively hurts other architectures which do have different constraints than x86. Any architecture which can do IPI-less TLB flushes seriously wants to decide on their own whether a flush all is the better option or not. Blindly coalescing random address ranges makes this impossible as demonstrated. Aside of that I just wrote the patch for x86 in the first place because I couldn't be bothered to find and setup an ARM box to test on. Thanks, tglx