From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DDF44C433F5 for ; Wed, 22 Sep 2021 10:56:19 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 83781610A1 for ; Wed, 22 Sep 2021 10:56:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 83781610A1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:58088 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mSzvG-0004aF-Ea for qemu-devel@archiver.kernel.org; Wed, 22 Sep 2021 06:56:18 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51688) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mSzu2-0003kq-CB for qemu-devel@nongnu.org; Wed, 22 Sep 2021 06:55:02 -0400 Received: from mail-wr1-x434.google.com ([2a00:1450:4864:20::434]:43861) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mSzu0-00087h-BN for qemu-devel@nongnu.org; Wed, 22 Sep 2021 06:55:02 -0400 Received: by mail-wr1-x434.google.com with SMTP id w17so5377199wrv.10 for ; Wed, 22 Sep 2021 03:54:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=references:user-agent:from:to:cc:subject:date:in-reply-to :message-id:mime-version:content-transfer-encoding; bh=p/shQS68/YGywWxAsAVUUxnpd22nzEJE1moktyZV4S8=; b=IwefvRncBidtDXa71H7riBwzgMoeGmd5DEH6em+k5FZ0i5m1YQWDRBVK8Zxx5X8ZOM 7RYaQAdzAF//gyXLLHZqqVpoOnvGuKYihKyfNN2jtC93EiBqhBV5CHMR3FHv9i8o7u5g lQ0DPfopktv639iqxDFKv53xoffVcuMLmDj3poZQeAbEcw46H4AyWFELpwwF8qesqs8V J1sfyGFsbzPTjGOvSXIGmJ/sU4omFEXQc909WFs4TC/IH/faVgAvrSQJYhAhOnsWQ1pU Dr0IWt1Ko8t3F/YII4KRPTdlyLQdZA8WPyMB8hhfR8YaCNuDCpAcXlDtciJRghPt56+O d14A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:references:user-agent:from:to:cc:subject:date :in-reply-to:message-id:mime-version:content-transfer-encoding; bh=p/shQS68/YGywWxAsAVUUxnpd22nzEJE1moktyZV4S8=; b=M14PS76nKOGy7K4I4Sw6VULtWu8iXolz1uKhv4F1I7qOVSZxHG+Uf/Hao7f7M3B63c uiHCZg8W2nPhCrJKKWVnzXmYdufh3hYXooXUwb/A1FhhQsHdxtWy4y6KDKVUD6V4K2iy MD6GSPHLGtnO8YPXy4gD3EUzr12k7or4PgrSEAV4zR85yIl0rorijrjxx9YdsHV5t6po oibNS51gFk1zFu3nXQYi7umMk9h1HjaDu6yXWXFbTCBJ6yNIFslZxi6Lhp9MoiTESqBk p+8qQHMfjuhZeRimgvMHxetJycJU1947ofXq0AG/f9XZSvYa77fyxNBswMyoLs3R/inB yOqw== X-Gm-Message-State: AOAM531o4CKKbUqJSxuik5YJaHCE4NhVP1yZZm5gOoZ01r0nSHPql9lz ZWKugAymkQ9q9DWm6WW+kVsvuA== X-Google-Smtp-Source: ABdhPJwHQrpfF1uPkhPFlVH71TlEmrg5D6+pP9b47gjYg6yFrw95AEw1z71ILCVzbfl+8YOh8MYaNg== X-Received: by 2002:a7b:c086:: with SMTP id r6mr9955760wmh.46.1632308097815; Wed, 22 Sep 2021 03:54:57 -0700 (PDT) Received: from zen.linaroharston ([51.148.130.216]) by smtp.gmail.com with ESMTPSA id x14sm1619817wmc.10.2021.09.22.03.54.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Sep 2021 03:54:56 -0700 (PDT) Received: from zen (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id 5745E1FF96; Wed, 22 Sep 2021 11:54:56 +0100 (BST) References: User-agent: mu4e 1.7.0; emacs 28.0.50 From: Alex =?utf-8?Q?Benn=C3=A9e?= To: Kenneth Adam Miller Subject: Re: Change TCG cache size? Date: Wed, 22 Sep 2021 11:47:21 +0100 In-reply-to: Message-ID: <87a6k4op6n.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::434; envelope-from=alex.bennee@linaro.org; helo=mail-wr1-x434.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Kenneth Adam Miller writes: > Hello all, > > I just want to ask this one question: if I change the qemu tcg cache > size (TB_JMP_CACHE_SIZE), will that force any errors at run time? Hopefully not - for both user-mode and softmmu we take some care to ensure tb_jmp_cache_hash_func and tb_jmp_cache_hash_page return appropriately masked values for the table lookup. What has not been done since Emilio's work in 6f1653180f (tb-hash: improve tb_jmp_cache hash function in user mode) is a deeper look at the hit rate and bounce rate of the softmmu jump table hashing. Any suggested changes will need some benchmarking to show what difference it makes. --=20 Alex Benn=C3=A9e