From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966585AbbLQM04 (ORCPT ); Thu, 17 Dec 2015 07:26:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47650 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966522AbbLQM0y (ORCPT ); Thu, 17 Dec 2015 07:26:54 -0500 Message-ID: <5672AA0D.6050304@redhat.com> Date: Thu, 17 Dec 2015 07:26:53 -0500 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Seiichi Ikarashi CC: linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Radivoje Jovanovic , Mathias Krause , Ajay Thomas Subject: Re: [PATCH 1/3] powercap, intel_rapl, implement get_max_time_window References: <1450184532-21150-1-git-send-email-prarit@redhat.com> <1450184532-21150-2-git-send-email-prarit@redhat.com> <56724C0A.8000101@jp.fujitsu.com> In-Reply-To: <56724C0A.8000101@jp.fujitsu.com> Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/17/2015 12:45 AM, Seiichi Ikarashi wrote: > On 2015-12-15 22:02, Prarit Bhargava wrote: >> The MSR_PKG_POWER_INFO register (Intel ASDM, section 14.9.3 >> "Package RAPL Domain") provides a maximum time window which the >> system can support. This window is read-only and is currently >> not examined when setting the time windows for the package. > > I have been having a question here long time. > Maximum Time Window (bits 53:48) in MSR_PKG_POWER_INFO is only > 6-bit length even though Time Window for Power Limit #1 (bits 23:17) > and Time Window for Power Limit #2 (bits 55:49) in MSR_PKG_POWER_LIMIT > are both 7-bit length, not 6. While looking at the MSR settings I had exactly the same question! I too would like to know the answer. > > Do Intel guys have an answer for it? > > > The patch itself looks good to me. > Just minor comments below: > >> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c >> index cc97f08..f765b2c 100644 >> --- a/drivers/powercap/intel_rapl.c >> +++ b/drivers/powercap/intel_rapl.c >> @@ -493,13 +493,42 @@ static int get_current_power_limit(struct powercap_zone *power_zone, int id, >> return ret; >> } >> >> +static int get_max_time_window(struct powercap_zone *power_zone, int id, > > The 2nd arg "id" is not necessary. I'll drop this in v2. > >> + u64 *data) >> +{ >> + struct rapl_domain *rd; >> + int ret = 0; >> + u64 val; >> + >> + get_online_cpus(); >> + rd = power_zone_to_rapl_domain(power_zone); >> + >> + if (rapl_read_data_raw(rd, MAX_TIME_WINDOW, true, &val)) > > rapl_read_data_raw() can return -EINVAL and -ENODEV other than -EIO. > >> + ret = -EIO; > > Is it OK to limit ret to -EIO here? AFAICT it seems like it. The only error that can occur here (at least by the time this code is executed) is that there is a range error. -EIO seems appropriate. > >> + else >> + *data = val; >> + >> + put_online_cpus(); >> + return ret; >> +} >> + >> static int set_time_window(struct powercap_zone *power_zone, int id, >> u64 window) >> { >> struct rapl_domain *rd; >> int ret = 0; >> + u64 max_window; >> >> get_online_cpus(); >> + ret = get_max_time_window(power_zone, id, &max_window); >> + if (ret < 0) >> + goto out; >> + >> + if (window > max_window) { >> + ret = -EINVAL; >> + goto out; >> + } >> + >> rd = power_zone_to_rapl_domain(power_zone); >> switch (rd->rpl[id].prim_id) { >> case PL1_ENABLE: >> @@ -511,6 +540,7 @@ static int set_time_window(struct powercap_zone *power_zone, int id, >> default: >> ret = -EINVAL; >> } >> +out: >> put_online_cpus(); >> return ret; >> } >> @@ -590,6 +620,7 @@ static struct powercap_zone_constraint_ops constraint_ops = { >> .set_time_window_us = set_time_window, >> .get_time_window_us = get_time_window, >> .get_max_power_uw = get_max_power, >> + .get_max_time_window_us = get_max_time_window, >> .get_name = get_constraint_name, >> }; >> >> diff --git a/drivers/powercap/powercap_sys.c b/drivers/powercap/powercap_sys.c >> index 84419af..7d77b83 100644 >> --- a/drivers/powercap/powercap_sys.c >> +++ b/drivers/powercap/powercap_sys.c >> @@ -101,7 +101,7 @@ static ssize_t store_constraint_##_attr(struct device *dev,\ >> int err; \ >> u64 value; \ >> struct powercap_zone *power_zone = to_powercap_zone(dev); \ >> - int id; \ >> + int id, ret; \ >> struct powercap_zone_constraint *pconst;\ >> \ >> if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \ >> @@ -113,8 +113,10 @@ static ssize_t store_constraint_##_attr(struct device *dev,\ >> if (err) \ >> return -EINVAL; \ >> if (pconst && pconst->ops && pconst->ops->set_##_attr) { \ >> - if (!pconst->ops->set_##_attr(power_zone, id, value)) \ >> + ret = pconst->ops->set_##_attr(power_zone, id, value); \ >> + if (!ret) \ >> return count; \ >> + return ret; \ > > An opposite question to above. > Is it OK not to limit the return value to -EINVAL here? > Do you want this function to return -EIO or something? In this case, no, because the define is used by other values. I think that would limit all erros in the set_* functions to be -EIO. P.