From owner-freebsd-virtualization@freebsd.org Sun May 5 00:54:53 2019 Return-Path: Delivered-To: freebsd-virtualization@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 0279F159D5DF for ; Sun, 5 May 2019 00:54:52 +0000 (UTC) (envelope-from akgupt3@gmail.com) Received: from mail-wr1-x42e.google.com (mail-wr1-x42e.google.com [IPv6:2a00:1450:4864:20::42e]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id B8E3677C3B for ; Sun, 5 May 2019 00:54:51 +0000 (UTC) (envelope-from akgupt3@gmail.com) Received: by mail-wr1-x42e.google.com with SMTP id v10so239061wrt.6 for ; Sat, 04 May 2019 17:54:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:cc; bh=6Loufd1vEuSj2mA4jQW1YdZWaxlJe78JhY8B3z78tiw=; b=BGsmYuLr1BfPKijr54UIqGhhmtAl4GyKpMT02xlymsvVE0A6IWfjoJ20xniPiWp+qj nRnXLHBEh0DQywgHebOlQX9sBg5aMeRbllq8X9DSv0NaEZF1yQY+7tvI1k0/BDXYxwP8 75+moxe/8yyH+ftL1vMd9fqd5x/uoK7KjIS3Y9Fj+54dQ3samQq1IAo4fJdAefuiMX+W 6sVx9nPJaW5E+LLQ2FUgfQnrUdHp/lk8FHLepjXcVK4IADac6+Loj4DLWzfn1PZk36VL VpIiViSkGxnf+y0FqHjOqg4ezZgdQhB8XtKJL0N1IU4iFrQSzVKhv3RCmarwMOhZRzGn r3bA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:cc; bh=6Loufd1vEuSj2mA4jQW1YdZWaxlJe78JhY8B3z78tiw=; b=ZW11JSqFduDZ693GoE1WzSppKHodeIHcgCdYzCv2VHAN/Q0fP6rzOHG3SDkSJ25wpX U/jmsJI1loq511/ajqYmnc8UBb/0dF/ZImZSJY58umdPoMeFpRk1lxK7aSvEOjdxfMGc OtT3czRQncuiUuTa0h1hjbT0zliDYOrCB/erwKWRair3/1t1pMCsFcpkRFuvtzf2aXoJ g86rgMGUrhcUVxca2V+z2NOfjMeCW7vKcfmu0L5dflbN1umXH+uY0ztwY4WPyiclojfR Wc4we+upQ6Jl2Fz4xkuQws+wsjAFm/y89lVf14zS2trmMaf1BZROOiSySodfcYpwpiW5 Uomg== X-Gm-Message-State: APjAAAWViIRAaMVJz3dZBXLVnTlsSRg6ltVB9Ju/6EyU3sQeWDQK9rr5 6NalNZLjKlGjXJfKe5hleTg41XgvBLgVQNt5bKk= X-Received: by 2002:adf:fc49:: with SMTP id e9mt10003066wrs.269.1557017690452; Sat, 04 May 2019 17:54:50 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Anish Date: Sat, 4 May 2019 17:54:39 -0700 Message-ID: Subject: Re: BSD11 vs BSD12 KVM performance Cc: "Bapat, Udayan" , "freebsd-virtualization@freebsd.org" X-Rspamd-Queue-Id: B8E3677C3B X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=BGsmYuLr; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of akgupt3@gmail.com designates 2a00:1450:4864:20::42e as permitted sender) smtp.mailfrom=akgupt3@gmail.com X-Spamd-Result: default: False [-4.40 / 15.00]; TO_DN_EQ_ADDR_SOME(0.00)[]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36]; FREEMAIL_FROM(0.00)[gmail.com]; MX_GOOD(-0.01)[cached: alt3.gmail-smtp-in.l.google.com]; DKIM_TRACE(0.00)[gmail.com:+]; RCPT_COUNT_TWO(0.00)[2]; MISSING_TO(2.00)[]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; NEURAL_HAM_SHORT(-0.67)[-0.669,0]; FROM_EQ_ENVFROM(0.00)[]; RCVD_TLS_LAST(0.00)[]; MIME_TRACE(0.00)[0:+,1:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; DWL_DNSWL_NONE(0.00)[gmail.com.dwl.dnswl.org : 127.0.5.0]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-virtualization@freebsd.org]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[e.2.4.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.5.4.1.0.0.a.2.list.dnswl.org : 127.0.5.0]; IP_SCORE(-2.72)[ip: (-9.04), ipnet: 2a00:1450::/32(-2.23), asn: 15169(-2.25), country: US(-0.06)]; RCVD_COUNT_TWO(0.00)[2] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 05 May 2019 00:54:53 -0000 Hi Udayan, Intel VM-x and AMD SVM allow hypervisor to intercept TSC access for save/restore of VM migration, so when these intercepts are enabled, rdtsc will require switch between root and non-root mode which is expensive and may cost few hundreds of cpu cycles. Is it possible that one has these intercepts always enabled even when migration is not started? -Anish