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[122.211.248.161]) by smtp.gmail.com with ESMTPSA id e2sm6012727pfn.141.2021.09.13.00.18.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Sep 2021 00:18:24 -0700 (PDT) From: Punit Agrawal To: John Kacur Cc: punit1.agrawal@toshiba.co.jp, linux-rt-users@vger.kernel.org Subject: Re: [PATCH 4/5] rteval: hackbench.py: Enable running on a system with low memory References: <20210901080816.721731-1-punitagrawal@gmail.com> <20210901080816.721731-5-punitagrawal@gmail.com> <4273ee11-b665-53e1-57b6-1e8f443168a5@redhat.com> Date: Mon, 13 Sep 2021 16:18:21 +0900 In-Reply-To: <4273ee11-b665-53e1-57b6-1e8f443168a5@redhat.com> (John Kacur's message of "Thu, 9 Sep 2021 08:46:11 -0400 (EDT)") Message-ID: <8735q99c5e.fsf@stealth> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org Hi John, John Kacur writes: > On Wed, 1 Sep 2021, Punit Agrawal wrote: > >> From: Punit Agrawal >> >> The hackbench workload refues to run on RockPro64, a hexacore 64bit >> Arm board with 4GB memory, complaining about insufficient memory >> per-core. >> >> On further investigation, it turns out that workload is using an >> arbitrary limit of 0.75 GB/core but will quite happily run on much >> lower lower memory systems. >> >> Instead of preventing execution, convert the info message to a warning >> when the memory is lower than expected but continue execution. This >> should enable the workload to be used on a wider range of systems. >> >> Signed-off-by: Punit Agrawal >> --- >> rteval/modules/loads/hackbench.py | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/rteval/modules/loads/hackbench.py b/rteval/modules/loads/hackbench.py >> index 3b692070e9d9..ab028c495d8b 100644 >> --- a/rteval/modules/loads/hackbench.py >> +++ b/rteval/modules/loads/hackbench.py >> @@ -55,9 +55,8 @@ class Hackbench(CommandLineLoad): >> if ratio >= 0.75: >> mult = float(self._cfg.setdefault('jobspercore', 2)) >> else: >> - self._log(Log.INFO, "Low memory system (%f GB/core)! Not running" % ratio) >> + self._log(Log.WARN, "Low memory system (%f GB/core)!" % ratio) >> mult = 0 >> - self._donotrun = True >> >> sysTop = SysTopology() >> # get the number of nodes >> -- >> 2.32.0 >> >> > > I'm not sure that I can accept this. The number isn't entirely arbitrary, > it's based on verifying machines as realtime capable for customers, in > which case I'd rather it fails early. I think there's a misunderstanding. The above check only prevents the hackbench workload from running - which takes ~2-3MB in the default configuration on the board I tested. rteval (along with cyclictest, kcompile and other workloads) executes without any issues. In terms of memory requirements for real time systems, I am not sure there is a single number that is valid across all applications or systems. Any such requirement only manages to alienate certain class of rteval users. I thought a warning was a good compromise. I am hoping you will reconsider the need to introduce a user option for this case. > Maybe there is some other way to indicate that the user is okay with > lower memory system, such as passing an --embedded flag or something > of that nature? If the above doesn't convince you, I will look to adding an option. How about calling the option "--low-memory-system" to clearly state what it enables. "Embedded" is not well-defined and hard to guess what it relates to.