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[184.147.143.99]) by smtp.gmail.com with ESMTPSA id s6sm4388374iow.1.2021.09.13.05.52.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Sep 2021 05:52:40 -0700 (PDT) Date: Mon, 13 Sep 2021 08:52:39 -0400 (EDT) From: John Kacur To: Punit Agrawal 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 In-Reply-To: <8735q99c5e.fsf@stealth> Message-ID: <6d2f87e-f4c-3371-d990-ce1ca67bcbf@redhat.com> References: <20210901080816.721731-1-punitagrawal@gmail.com> <20210901080816.721731-5-punitagrawal@gmail.com> <4273ee11-b665-53e1-57b6-1e8f443168a5@redhat.com> <8735q99c5e.fsf@stealth> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org On Mon, 13 Sep 2021, Punit Agrawal wrote: > 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. > You're right, the original code only prevents hackbench from running, it doesn't cause rteval to fail early. Hmmn, it almost seems like the original code was a development hack that wasn't removed. Not sure, give me a short time to think about it. John