From nobody Tue Aug 12 15:23:07 2025 X-Original-To: virtualization@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4c1ZyN0g0Jz64xn3 for ; Tue, 12 Aug 2025 15:23:08 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R10" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4c1ZyM5pLTz3hlW for ; Tue, 12 Aug 2025 15:23:07 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1755012187; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pGTa1v+J3kMG09h6MT4VW1aTLfuqRtrIGhCygj4LeZo=; b=mkxXbnjjYHLacNUdGtYt1i/uM3p9iY4Z92FxbPx2vQVd4GaiG6mt+GjWK9+Umq5tGXF/Iu wqWanPQGfTqXkWuAgn5Yvzid68lVjx43AMWZjrV6M4IF8DgX8pgP5zwh4y3ysnASpwRQly I5Xix0ojAe0dtIEUuKqpJaJOPIoE3GzFlSVsHClQ2tAe2vwyD/Q+v0tc+BEMFTj7Hv+Njn D7MPbyIuFOPNZ8x452w+Ak/piSiNZZgckhfKx63OUwprAPTrOgIuc83WTpxwGHvCFgXrNc QDbtLULJKvkKRjrliUgxgqskjTePgx6jx4txhl7BVGVEhz0D6VhWdBpcHSKNMA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1755012187; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pGTa1v+J3kMG09h6MT4VW1aTLfuqRtrIGhCygj4LeZo=; b=v5+MafoPEPiQuhGB/xvzHuW0QMujGU/ATKm9YCLf1qMiJY00GP2UmcDfeAxyfUAHutcFRL mwuormQfyQL/zaz/0kfQgjj/6QP5H592VYaKyHwfVdU5eXmf6Jt/Nuz6BDvmat78866pCz aBR7AvrygXVZXjd5W9092hm5Gpuf//ULpnz4/gCq3D61dRuSvfi9VGh8EQBmFj63ylOJBR sSZpWfERuSy49j4voSDZGWNauQnz4GScUWTBV3GBIdY8hdixSj1a6B0/o9TSrKWCq6yeSD KhtTez8VStq+ZSKQKRCNeBS/rgXsHt1IXLAcw4uoClsW8VlJIiEtKMorMAgzBA== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1755012187; a=rsa-sha256; cv=none; b=vCkcMaqHsadfDsY8dnash418TVOGuWqdCntRN6pPaYAshWlacGXKU4Uma93NKwXHFjx04B r1E7m1SXCa2sP0rcGgn+qdkWQesTkCSXmi8yvWl/LY5FRUQRKosHFb86DZ7dyKbQM45qWD EShSzw3oY5ycQz94G4DNdT87cIVV77eAnCr8srd1KLYOibfcSM31WoqZZi3OHLUgOgTF+R t1etGpFd5uaGOE3ORTrPRaphPTun86TGacskip/QcYR1x/XXTalFT4l3+ImWvppBnNoL7r /8uFHgckEha3P0uauQpkL8Am+Z/1wZZlKl3iDYG3AMB1Pg29Nlj9l6jIm1DvaQ== Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4c1ZyM5Jd1zk4L for ; Tue, 12 Aug 2025 15:23:07 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id 57CFN7MS062800 for ; Tue, 12 Aug 2025 15:23:07 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 57CFN7BO062799 for virtualization@FreeBSD.org; Tue, 12 Aug 2025 15:23:07 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: virtualization@FreeBSD.org Subject: [Bug 256781] EC2 Nitro: TSC-low timecounter lags Date: Tue, 12 Aug 2025 15:23:07 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 13.0-RELEASE X-Bugzilla-Keywords: needs-patch, needs-qa X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: cperciva@FreeBSD.org X-Bugzilla-Status: Closed X-Bugzilla-Resolution: Overcome By Events X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: virtualization@FreeBSD.org X-Bugzilla-Flags: maintainer-feedback? mfc-stable13? mfc-stable12? X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="UTF-8" X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated List-Id: Discussion List-Archive: https://lists.freebsd.org/archives/freebsd-virtualization List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: freebsd-virtualization@freebsd.org Sender: owner-freebsd-virtualization@FreeBSD.org MIME-Version: 1.0 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D256781 --- Comment #44 from Colin Percival --- I vaguely recall that another VM system implemented 0x40000010 on the basis= of "it's an unofficial standard now". Maybe qemu? Credit goes to Alex Graf f= or making me aware of this anyway. A few years ago when I was hacking on FreeBSD/Firecracker I wrote up a patch to make Firecracker expose that leaf= too -- the only reason it didn't go into the tree was because they were in the middle of reworking how they exposed CPU types to guests so it wasn't a good time for the patch to land. It always annoyed me that Lambda was paying the cost of a Linux TSC calibration loop on every cold start, but I don't work = for Amazon and there was only so long I could keep waving the "look guys you're leaving money on the table here" flag. And yes, we make use of the Xen leaf as well on those systems (not that we particularly care about this in EC2). --=20 You are receiving this mail because: You are the assignee for the bug.=