linux-kernel - Re: [PATCH v2 0/6] Assume sysfs event names are always lowercase

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Date: Tue, 23 Apr 2024 08:53:47 +0200
From: Thomas Richter <tmricht@...ux.ibm.com>
To: Ian Rogers <irogers@...gle.com>, Kan Liang <kan.liang@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>,
        Jonathan Corbet <corbet@....net>, Bjorn Helgaas <bhelgaas@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Jing Zhang
 <renyu.zj@...ux.alibaba.com>,
        James Clark <james.clark@....com>,
        Ravi Bangoria <ravi.bangoria@....com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v2 0/6] Assume sysfs event names are always lowercase

On 4/23/24 05:17, Ian Rogers wrote:
> By assuming sysfs events are lower case, the case insensitive event
> parsing can probe for the existence of a file rather then loading all
> events in a directory. When the event is a json event like
> inst_retired.any on Intel, this reduces the number of openat calls on
> a Tigerlake laptop from 325 down to 255.
> 

Ian, sorry for the late reply.
On s390 the events in the sysfs tree are all upper case:

[root@...lp67 ~]# ls -l /sys/devices/cpum_cf/events/ | head -10
total 0
-r--r--r-- 1 root root 4096 Apr 17 14:47 AES_BLOCKED_CYCLES
-r--r--r-- 1 root root 4096 Apr 17 14:47 AES_BLOCKED_FUNCTIONS
-r--r--r-- 1 root root 4096 Apr 17 14:47 AES_CYCLES
-r--r--r-- 1 root root 4096 Apr 17 14:47 AES_FUNCTIONS
-r--r--r-- 1 root root 4096 Apr 17 14:47 BCD_DFP_EXECUTION_SLOTS
-r--r--r-- 1 root root 4096 Apr 17 14:47 CPU_CYCLES
-r--r--r-- 1 root root 4096 Apr 17 14:47 CRSTE_1MB_WRITES
-r--r--r-- 1 root root 4096 Apr 17 14:47 DCW_OFF_DRAWER
-r--r--r-- 1 root root 4096 Apr 17 14:47 DCW_OFF_DRAWER_MEMORY
[root@...lp67 ~]# 

Same is true for all other PMUs (currently 5 and growing).

Is there a branch to pull to try out the effect of your patch on s390?

Thanks Thomas
-- 
Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany
--
IBM Deutschland Research & Development GmbH

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