From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932340AbbLGRuK (ORCPT ); Mon, 7 Dec 2015 12:50:10 -0500 Received: from mail-oi0-f46.google.com ([209.85.218.46]:34985 "EHLO mail-oi0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755382AbbLGRuJ (ORCPT ); Mon, 7 Dec 2015 12:50:09 -0500 MIME-Version: 1.0 Date: Mon, 7 Dec 2015 23:20:08 +0530 Message-ID: Subject: Ques: [kernel/time/*] Is there any disadvantage in using sleep_range for more than 20ms delay ? From: Aniroop Mathur To: John Stultz , Thomas Gleixner Cc: a.mathur@samsung.com, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dear Mr. John and Mr. Thomas, Greetings of the day !! This is Aniroop Mathur working on sensor kernel drivers for last 3 years. Recently, In my driver code, I have been changing msleep to usleep_range. But I got stuck at one point and could not find proper answer on internet. Could you please help to answer my query as mentioned below ? >>From the kernel documentation, I understood that it is better to use usleep_range for 10 us - 20 ms delay. For delays 10ms+, it is mentioned to use msleep. If my understanding is right and considering HZ=100, Even for 33 ms delay, msleep would sleep for 40 ms, while usleep_range would sleep for 33 ms as desired. And for 40 ms delay, msleep and usleep_range both will wake up at desired time. Right ? As in the kernel documentation, it is mentioned to use msleep for 10ms+ delay, I am confused whether there would be any disadvantage in using usleep_range for higher delays values because normally drivers have variety of delays used (2, 10, 20, 40, 100, 500 ms). So, could you please help to confirm if there could be some problem in using usleep_range for higher delay values ? Thanks in advance ! Regards, Aniroop Mathur