From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f202.google.com (mail-yw1-f202.google.com [209.85.128.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8EFA5172791 for ; Tue, 28 May 2024 17:20:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716916844; cv=none; b=AkS7AAwG5mrZlBAXxgKQdahjQtWhn1LOaEA5rxPpym/LWgvUCdRO2cgI7SdBzXsEJYojDPRgaW8ALpg2fggisgB4smmqFINHQl836q95ehh4GPG6bw9FP9xEscH38mSyEXaunMInKTjzdUp1WMhPO60RKPEJay5NqxLEAZI8WNw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716916844; c=relaxed/simple; bh=dDYC97Td061WUI8ezos3IQIWa3Zqeedt1t0yL+iUhF0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=mVjK1BlRPSHYrjOmvj/3+JTEkI271nwPUD5CI8j920oiHwQT/kZbqSALAPwU30h3LWyEBJZL5YAgMl8PysfYOF59Uq+1l7Ce90Mx5Q4zH7o690zFXHfvbvkRTvIdPxLLgsv7yHBUJ5WDxjMjCaA7gZmpKhVmYQXw+IqDMA+Ttf0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=fP7mfKkd; arc=none smtp.client-ip=209.85.128.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="fP7mfKkd" Received: by mail-yw1-f202.google.com with SMTP id 00721157ae682-62a1e9807c0so367167b3.0 for ; Tue, 28 May 2024 10:20:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1716916842; x=1717521642; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=Zdjf+Oso2zYeF2PeKJeu2LDUmFwWwvMWQeLwzdtyzdA=; b=fP7mfKkd3Tko2HIBIhB1hqx+ilT/lqmdKt4Fu++1hZ2tVIGnpHiifbIztFvuEy92AV 7PUCWs+y3N4oqd97Qqf13KlJ/sll5zAxxCtApI0rLpgsnOHkEOUj/wsIYmUtT/DC7NR4 5wGJL6rv9B+elFUdJEtzSI8xGraWr5P5VqQz0zT6brrM4wGlLPoiSjZursJ8BBohHgdr vEn1sQTk0aomHjWh3QKLPEdpM3yrh6dc5lFk3J40ZXAs0abAORWbktjEyU6YS4/nfbDD 0aRjsQ8pOY5K6TPA2H0OlGpsyrYKn7DpmqksQ5V7lcWJufqWQiFkIFX8M2jcN2pbgkhS lDdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716916842; x=1717521642; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Zdjf+Oso2zYeF2PeKJeu2LDUmFwWwvMWQeLwzdtyzdA=; b=jf0bWi26oF0WYdlzfOa82QXMEImW5mWQqX0en/F2b253F7of9qASaD8xXknX9Iwmrb RWonKR/fSXsV/CNg06lUBzM/rB8Usub/jxOkAr7OOWY6WiKU1ijFDKW4T5FCxeq2dX7Y Erqu9h7qDtO5AQkoaopIeN+rCcNSp1oPj59v7t74nna5nq5gh11TIdQkOK22PpjQspON /2nV9AaN2ZMMf2CQ4YBQ4LqLye4QlCdyCvltZNpGOyRx5a0fxS1sZfyRoZhdlSvDrLUk hxITCAOvcPNShPUU/wxsRNjhxTe9qKX3FsEUMzbmGUsTUJxpacZp+yOxX9lhvLNv1QJO Tk1A== X-Gm-Message-State: AOJu0YzQlEAcYvmeluR/mZpDpnLEY193Md0E64XZc6eNxzbOa4wcLigH 5MRzwtsQwS3c1FbKOJ9cYp2Wr41whmxmJRqpvMa8cCM0b2NnzkLE+TVsNd6+/5BkSIgcyOSkO+z f1Q== X-Google-Smtp-Source: AGHT+IGyObRR3eB9tl2o8vJjV9M0MJA3mbgnFb0Hxd6EwyJVem/xg2La75HbR3IlKxgE33PcRAEX5whkViI= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:690c:450c:b0:618:5009:cb71 with SMTP id 00721157ae682-62a07647b4amr34639717b3.5.1716916842572; Tue, 28 May 2024 10:20:42 -0700 (PDT) Date: Tue, 28 May 2024 10:20:41 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: Message-ID: Subject: Re: [Bug 218739] pmu_counters_test kvm-selftest fails with (count != NUM_INSNS_RETIRED) From: Sean Christopherson To: bugzilla-daemon@kernel.org Cc: kvm@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Mon, May 27, 2024, bugzilla-daemon@kernel.org wrote: > I also see this test fail sometimes (once per hour or so of continuous running) > and in my case it fails because 'count != 0' assert on > INTEL_ARCH_LLC_MISSES_INDEX event and only for this event. > > The reason is IMHO, is that it is possible to have 0 LLC misses if the cache > is large enough and code was run for enough iterations. The test does CLFUSH{,OPT} on its future code sequence after enabling the counter. In theory, that's should guarantee an LLC Miss. Hmm, but this SDM blurb about speculative loads makes me think past me was wrong. (that is, data can be speculatively loaded into a cache line just before, during, or after the execution of a CLFLUSH instruction that references the cache line).