From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: Jinhui Guo <guojinhui.liam@bytedance.com>,
<linux-kernel@vger.kernel.org>
Cc: <catalin.marinas@arm.com>, <linux-arm-kernel@lists.infradead.org>,
<lizefan.x@bytedance.com>, <robin.murphy@arm.com>,
<will@kernel.org>
Subject: Re: [PATCH] arm64: cpufeature: Expose the real mpidr value to EL0
Date: Wed, 13 Sep 2023 14:11:36 +0100 [thread overview]
Message-ID: <20230913141136.00006a47@Huawei.com> (raw)
In-Reply-To: <20230913105133.2902-1-guojinhui.liam@bytedance.com>
On Wed, 13 Sep 2023 18:51:33 +0800
Jinhui Guo <guojinhui.liam@bytedance.com> wrote:
> > As a follow up question, is there some information that is missing from
> > current topology description? (there is lots missing but I'm curious
> > as to what might matter for your use case!)
>
> We want to know the infomation about dies to advoid memroy accessing
> across dies (some settings like 2 numa per die).
The NUMA access characteristics should give you the info you want - it's
the variation in latency and bandwidth between dies that matters, not that
they are dies. If you got really bad access characteristics across a die
that info would be equally useful.
I think it is not that this is a die that matters, but rather that there
are groups of Numa nodes with relatively small differences in access
characteristics, then others with much larger variation (and I assume
a layer above that which is inter socket which is even worse).
The info is in HMAT, but the kernel presentation of HMAT is rather limited
currently - so you may want to look at extending what is visible in sysfs
from that table.
Thanks,
Jonathan
>
> thanks,
>
> Jinhui Guo
>
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next prev parent reply other threads:[~2023-09-13 13:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-12 3:52 [PATCH] arm64: cpufeature: Expose the real mpidr value to EL0 guojinhui.liam
2023-09-12 8:31 ` Robin Murphy
2023-09-12 10:51 ` Jonathan Cameron
2023-09-13 10:51 ` Jinhui Guo
2023-09-13 13:11 ` Jonathan Cameron [this message]
2023-09-13 9:44 ` guojinhui
2023-09-13 11:23 ` Robin Murphy
2023-09-13 13:06 ` Jonathan Cameron
2023-09-13 18:57 ` Robin Murphy
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