From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-189.mta1.migadu.com (out-189.mta1.migadu.com [95.215.58.189]) (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 ED10E449ECA for ; Tue, 16 Jun 2026 15:43:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.189 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781624583; cv=none; b=Qhvdq3tF9Z9PppT5r5FLaiyhvuo7WvIFgK5S4tkQX2Pe4wtYioF80/Fm+MU2qi93tWegsOvUOaLZJxJ9zjpMhERYRJTRCa56JhEVaxl0UV4zgqAbOZCqgM6GxRMOXYVT2xF/Nq1/1RBKw3HPqCyG+iVCNKEw4MuHqUi9VNGwIIc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781624583; c=relaxed/simple; bh=z0Yi+ccp1237LA8Mtk3EaNcrP3jhyczTa9ge8x2+pi4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=asNWM6xkfDuZ6PN3/nGKZQJWm4K3rObnZtCI30d2GVo5j6lZCllI7VoUG6gDZFkBbDiVYqbsX7p392sxzgRQoiXUFLU0o0pISxY2ihcaKr385tjQv05o2l8YL2POzM6AiTh0K0BvQTylbrrIrTotGggGyWtCkENDmX48AfyZ9uc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=p/3+HO9C; arc=none smtp.client-ip=95.215.58.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="p/3+HO9C" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1781624578; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=z0Yi+ccp1237LA8Mtk3EaNcrP3jhyczTa9ge8x2+pi4=; b=p/3+HO9CuS+TZrK8V5uNvwBhzi8hcizba1dcyw9SgkkGiHG57B7LJ0YnhLDLYJKX9PfEhH 1VMxkstwQk++3e8ERVIU/BL80NHY82HB2T0ivY9FroTtSFyiYr5NXyx/5MOYwvM5/Kgx4e AzNtuM4JeimJ7YTy9Lnfo7P1ylYnxHA= From: Tao Cui To: maobibo@loongson.cn Cc: chenhuacai@kernel.org, cui.tao@linux.dev, cuitao@kylinos.cn, kernel@xen0n.name, kvm@vger.kernel.org, loongarch@lists.linux.dev, zhaotianrui@loongson.cn Subject: Re: [PATCH v4 3/3] KVM: selftests: loongarch: Add PV TLB flush performance test Date: Tue, 16 Jun 2026 23:42:31 +0800 Message-ID: <20260616154231.10982-1-cui.tao@linux.dev> In-Reply-To: <4efcc81b-bf7e-4d78-ba82-9f4590673486@loongson.cn> References: <4efcc81b-bf7e-4d78-ba82-9f4590673486@loongson.cn> Precedence: bulk X-Mailing-List: loongarch@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Tao Cui Thanks, and I share the stability concern. I don't want to land something that adds risk for a feature that isn't clearly earning its place yet. > Do you have real workload to show the benefits of the PV TLB flush, > and which TLB APIs should be hooked. Completely fair, and to be upfront I don't have a large-scale real-world workload to point to yet. So my plan is to build a set of local test scripts that simulate as many usage scenarios as possible: mmap/fork-heavy paths, kernel-range flushes, and an overcommitted setup where vCPU preemption is frequent. I'll report the IPI and TLB-flush overhead with and without the feature, broken down per flush API. The coverage is synthetic rather than a single flagship workload, but hopefully it can at least give us a rough, preliminary sense of whether the feature is worth pursuing. Thanks, Tao