From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-x22b.google.com (mail-pa0-x22b.google.com [IPv6:2607:f8b0:400e:c03::22b]) by lists.bufferbloat.net (Postfix) with ESMTPS id 8600E3B2E7 for ; Tue, 5 Jan 2016 20:22:06 -0500 (EST) Received: by mail-pa0-x22b.google.com with SMTP id do7so5297361pab.2 for ; Tue, 05 Jan 2016 17:22:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-type:content-transfer-encoding; bh=UGvGul5bUb8kC40dP8O8Q4yhdyRSGsO9rSrsZ1EGap8=; b=tx/y0kEHx/EQuhhZ+0PUVKCzFYbjIyblgTq0LoKSrllQa9FJCMLVMweCgG6yrizL27 w4Vslplw5QFvkkOrsYDflLWkDAVT/FfzDWV3yRAqav6IRLbe9+9A4BKM0Ye73fiVQpE5 3ib8wIPRQ0OqFxLfea2jernlPf7UMP6UKsNFcIfZAFYduCkioIpkVLxm+MBpOrCAfYo6 IDHNV8CQ7dKzNDclqQM6yvNYZnmJdwZz4DsWmVaC+xv47h5EJ2ifASWfcJeS13aAIMzn p+PZsJQExJ0kLhhpJbzVyJfO3bFiEXwZ6yWpyR9j55iiDvqZzgz/zQ2w1CzOuqPFBvgb PfgQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-type:content-transfer-encoding; bh=UGvGul5bUb8kC40dP8O8Q4yhdyRSGsO9rSrsZ1EGap8=; b=hyc/x8a1PJqexRoZFh0/P+cbZYK+B070koVCNC5pqbCE9EryOgNrpeCQqjDRNNVxN0 Mg09rk8mpHn47NSoXvgJzsCLBEpNmuQRpNOulT50oP8knbHPws35BPAtGCjOeYJLC0ny mhfWEbB0zWHV6GOg42x0cih8Ltv7cRJ4tkYzPqDxlIOArXlYGftcKcxggp34MbQXluqf /+TajMGJVBcr6/RC33iKXEEX1X+8Fod0kDw15BSG3Qh3ZYi13XG4V8jXNdWcKB66wPzY rkaNPsmmq992E2MTVSsRJ/EXlQRsHaM2RiwITNKRCptx+QcXvolBQaViY0ZWDfZi1c21 xFmw== X-Gm-Message-State: ALoCoQkV9ZP8L4AZvol3T0ZKTbMeI1jMWymiB5DUQE7JID/a1WcIo2P8qSE4VJWc7jHVqg2FfgYt1upKH7YxV3GifgqkDIIFKw== X-Received: by 10.66.164.196 with SMTP id ys4mr137822597pab.119.1452043324018; Tue, 05 Jan 2016 17:22:04 -0800 (PST) Received: from xeon-e3 (static-50-53-82-155.bvtn.or.frontiernet.net. [50.53.82.155]) by smtp.gmail.com with ESMTPSA id 79sm62462008pfs.42.2016.01.05.17.22.03 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 05 Jan 2016 17:22:03 -0800 (PST) Date: Tue, 5 Jan 2016 17:22:11 -0800 From: Stephen Hemminger To: "Steinar H. Gunderson" Cc: "bloat@lists.bufferbloat.net" Message-ID: <20160105172211.52c67535@xeon-e3> In-Reply-To: <20160106005537.GA20844@sesse.net> References: <165DB6E9-A6DD-4626-B6AA-E1B2DBA0B5FA@gmail.com> <568C1209.5050403@taht.net> <20160106000151.GA5332@sesse.net> <20160106002213.GA8486@sesse.net> <20160105165314.118713f3@xeon-e3> <20160106005537.GA20844@sesse.net> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Bloat] Hardware upticks X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Jan 2016 01:22:06 -0000 On Wed, 6 Jan 2016 01:55:37 +0100 "Steinar H. Gunderson" wrote: > On Tue, Jan 05, 2016 at 04:53:14PM -0800, Stephen Hemminger wrote: > >> Also, I've never ever seen the actual context switch turn up high in a perf > >> profile. Is this because of some sampling artifact? > > Yes, especially with Intel processors getting more and more SSE/floating point > > registers. > > But those are not saved on context switch to the kernel, no? (Thus the rule > of no floating-point in the kernel.) Only if you switch between userspace > processes Right that just punts the work to the kernel when it context switches to next process.