From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id ED1B31FEAA for ; Tue, 19 Jul 2016 19:03:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751587AbcGSTD2 (ORCPT ); Tue, 19 Jul 2016 15:03:28 -0400 Received: from mail-wm0-f42.google.com ([74.125.82.42]:38907 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751280AbcGSTD0 (ORCPT ); Tue, 19 Jul 2016 15:03:26 -0400 Received: by mail-wm0-f42.google.com with SMTP id o80so38055891wme.1 for ; Tue, 19 Jul 2016 12:03:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=opRUxoqRkguvyR8svhi9XDfEOLMSVn9NGPXxPO4NKYY=; b=N+IN+I7/EJBsOrL9C7pyvV/a70q0GE+R5VEbFxUzAXxUI3snuZTtkLQFUC2nNKH9Cu 5qyNtk5aEZbzjPkgj8CUIsUmzy/dVKYA6TkCLXjfuNFQTpMwZurZ0ev/8T9f1MU3Cv24 ZC266UJIu9pM45GIiW4Ohu/W+7HXU8KadzUvfMGhVuWvOKsohkHuKzruvxIqq3Gnr9TY K+jAz3/ISANPnWju7xl93Gnru49QdXRoyE6t5Lkn96BxFObtaZDCKzkCZ2xUz/6mNiBT PqT58lrh+k5bwe1gF/VcBbQE0gb3c04gvWBsupTKPzLb/YR5Ilq2Em3Y5OQ+xktVkw1l 2Pfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=opRUxoqRkguvyR8svhi9XDfEOLMSVn9NGPXxPO4NKYY=; b=T+GP4az0T5aCBITGoKtoM14LUSAvPMRXeiqt3HJ0UxJVhDtk7CuYmEdB9lRwvItgnb cjm/w3LsnWZznE3Nvj2xbX0cF15vxnUAa6E3XVNmKMIO9Gk8SQZvlV9wICr8BNwhVwZ+ iT+GYMjHwIvFJi4XvUr33gV8iUlBO+5zraq0Y3PHdubzvkdqs9tgF6y0dak8COiSkKOA 46whG6jNW2BDCph+4Y46nFD51tp3S2tlTSc07okK3PBa2oCjh8aXdlKAS5nXnaR2jAyc 06a0lLLuK0bko/luBoE71jqKaG4m4MGQFoT2FZBcdAtYWCVFOE/W5mdMzf9+WL9QCFwV f1Vw== X-Gm-Message-State: ALyK8tIJXnVBFEBsxx+qFbX3Ajg38MWOold6Fl1Dvd27r+9Z3B0PAZVDhlG+W+K6aOeW4sQyghcxtuEuLxz3BBnv X-Received: by 10.28.129.197 with SMTP id c188mr6565762wmd.46.1468955004859; Tue, 19 Jul 2016 12:03:24 -0700 (PDT) MIME-Version: 1.0 Received: by 10.28.167.87 with HTTP; Tue, 19 Jul 2016 12:03:24 -0700 (PDT) In-Reply-To: References: <1468880498-30235-1-git-send-email-jonathantanmy@google.com> From: Jonathan Tan Date: Tue, 19 Jul 2016 12:03:24 -0700 Message-ID: Subject: Re: [PATCH v2] fetch-pack: grow stateless RPC windows exponentially To: Stefan Beller Cc: "git@vger.kernel.org" , Jonathan Nieder , Junio C Hamano Content-Type: text/plain; charset=UTF-8 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Tue, Jul 19, 2016 at 9:46 AM, Stefan Beller wrote: > Care to elaborate on why you choose 11/10 as growth factor? > > (As someone who has a tick in micro optimizing: > 9/8 is roughly the same exponent, but the division > by 8 is easier as it is just a shift by 3. Similar 17/16) I don't have a specific reason for 11/10 as opposed to, say, 9/8 - I think that the time taken to execute this line is negligible compared to what's done in the calling code, but I'll change it to 9/8 if there is another reason for me to send another patch. > I guess one design criterion was 10 being a round number? > Does it make sense to experiment with the factor at all? > Digging into that, LARGE_FLUSH originates from 6afca450c3f, > (2011-03-20, fetch-pack: progressively use larger handshake windows), > and before we only had a linear growth. > > So I guess what I do not understand is why we need to slow down the > exponential growth at all? The current code has an exponential (a' = a * 2) then a linear (a' = a + 1024) growth. I'm not slowing down the exponential growth - that part is retained. I'm replacing the linear growth with another conservative exponential growth (a' = a * 11 / 10).