From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E9F04736E for ; Tue, 24 Oct 2023 22:31:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="VNspa/Yt" Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9524210FF; Tue, 24 Oct 2023 15:31:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=0xrKrG6QLKZInY7sNS1L6a1MY23Abv3L3T0w5lz/TMA=; b=VNspa/YtTP5+n3bl8xr0Vi9mpW aY5dzdce1UF2qLu4fOB6a+NS8h9aviD7kgHLrvrJRwwYz+/ynf2FK/xBXtLrgfUMNvha6Lys9vVnH CgUYX/75kt5d4Wi+9dcrgAidikQg1M0cDP9kMG+tRl1SAsyonyJTGEVdt1lVeN0G8SHu4mNhs1BdT urnbZzaSJFWlZOob24Il0AQdI5BTM1yVyHWxfabm2J/YClX/enU6iX7M+d7DYwuXkcW33EEKF4q4Z KSH8yK2Wp3U8vUbqz4Cqe/mu21CEbwwWUTH+BDkutTyfvqpH+RbSie9cS4o2IRONDl8mxTdEZ0LMd DnGHQGHw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qvPuq-00FpoV-0q; Tue, 24 Oct 2023 22:30:29 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id BBD0E300451; Wed, 25 Oct 2023 00:30:23 +0200 (CEST) Date: Wed, 25 Oct 2023 00:30:23 +0200 From: Peter Zijlstra To: "Luck, Tony" Cc: "H. Peter Anvin" , Pawan Gupta , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "x86@kernel.org" , Josh Poimboeuf , "Lutomirski, Andy" , Jonathan Corbet , "Christopherson,, Sean" , Paolo Bonzini , "ak@linux.intel.com" , "tim.c.chen@linux.intel.com" , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , "kvm@vger.kernel.org" , Alyssa Milburn , Daniel Sneddon , "antonio.gomez.iglesias@linux.intel.com" , "Milburn, Alyssa" Subject: Re: [PATCH v2 1/6] x86/bugs: Add asm helpers for executing VERW Message-ID: <20231024223023.GI33965@noisy.programming.kicks-ass.net> References: <20231024-delay-verw-v2-0-f1881340c807@linux.intel.com> <20231024-delay-verw-v2-1-f1881340c807@linux.intel.com> <20231024103601.GH31411@noisy.programming.kicks-ass.net> <20231024163515.aivo2xfmwmbmlm7z@desk> <20231024163621.GD40044@noisy.programming.kicks-ass.net> <20231024164520.osvqo2dja2xhb7kn@desk> <20231024170248.GE40044@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Oct 24, 2023 at 06:49:07PM +0000, Luck, Tony wrote: > > the only overhead to modules other than load time (including the runtime linking) is that modules can't realistically be mapped using large page entries. > > If there were some significant win for using large pages, couldn't the There is. The 4k TLBs really hurt. Thomas and me ran into that when doing the retbleed call depth crud. Similarly Song ran into it with BPF, they really want eBPF JIT to write to large pages.