Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [net-next,v3] tcp: Improve setsockopt() TCP_USER_TIMEOUT accuracy
To:     Jon Maxwell <jmaxwell37@gmail.com>, davem@davemloft.net
Cc:     edumazet@google.com, ncardwell@google.com, David.Laight@aculab.com,
        kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        jmaxwell@redhat.com
References: <20180710065147.27647-1-jmaxwell37@gmail.com>
 <3f856638-52bc-6630-a3d2-2b50f1bf7e48@gmail.com>
From:   Eric Dumazet <eric.dumazet@gmail.com>
Message-ID: <c29f1535-3c5d-e588-862c-ba948363c973@gmail.com>
Date:   Tue, 10 Jul 2018 05:48:22 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.6.0
MIME-Version: 1.0
In-Reply-To: <3f856638-52bc-6630-a3d2-2b50f1bf7e48@gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 07/10/2018 05:38 AM, Eric Dumazet wrote:

> Note that if we always do jiffies_to_msecs(icsk->icsk_user_timeout) in TCP,
> we also could change the convention and store msecs in this field instead of jiffies.
> 
> That would eliminate the msecs_to_jiffies() and jiffies_to_msecs() dance.
> 
> (That would be done in a patch of its own, of course)

tcp_keepalive_timer() does use icsk->icsk_user_timeout directly in jiffies unit,
but considering keeapalive timers are rarely used, this point would have to
do the msecs_to_jiffies() conversion.