From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Frank Rowand <frowand.list@gmail.com>
Cc: devicetree@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
Rob Herring <robh+dt@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC] Efficiency of the phandle_cache on ppc64/SLOF
Date: Mon, 2 Dec 2019 12:07:32 +0100 [thread overview]
Message-ID: <20191202110732.4dvzrro5o6zrlpax@linutronix.de> (raw)
In-Reply-To: <e1f232f5-3847-a519-5cce-95a26512e82b@gmail.com>
On 2019-11-29 20:14:47 [-0600], Frank Rowand wrote:
> The hash used is based on the assumptions you noted, and as stated in the
> code, that phandle property values are in a contiguous range of 1..n
> (not starting from zero), which is what dtc generates.
>
> We knew that for systems that do not match the assumptions that the hash
> will not be optimal. Unless there is a serious performance problem for
> such systems, I do not want to make the phandle hash code more complicated
> to optimize for these cases. And the pseries have been performing ok
> without phandle related performance issues that I remember hearing since
> before the cache was added, which could have only helped the performance.
> Yes, if your observations are correct, some memory is being wasted, but
> a 64 entry cache is not very large on a pseries.
okay, so it is nothing new and everyone is aware of the situation. I
move on then :)
> -Frank
Sebastian
next prev parent reply other threads:[~2019-12-02 11:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-29 15:10 [RFC] Efficiency of the phandle_cache on ppc64/SLOF Sebastian Andrzej Siewior
2019-11-30 2:14 ` Frank Rowand
2019-12-02 11:07 ` Sebastian Andrzej Siewior [this message]
2019-12-03 4:12 ` Michael Ellerman
2019-12-03 4:28 ` Frank Rowand
2019-12-03 16:56 ` Rob Herring
2019-12-05 16:35 ` Sebastian Andrzej Siewior
2019-12-06 2:01 ` Frank Rowand
2019-12-09 13:35 ` Sebastian Andrzej Siewior
2019-12-10 1:51 ` Rob Herring
2019-12-10 8:17 ` Frank Rowand
2019-12-10 12:46 ` Frank Rowand
2019-12-11 14:42 ` Rob Herring
2019-12-06 1:52 ` Frank Rowand
2019-12-08 6:59 ` Frank Rowand
2019-12-03 4:03 ` Michael Ellerman
2019-12-03 18:35 ` Segher Boessenkool
2019-12-06 1:37 ` Frank Rowand
2019-12-06 23:40 ` Segher Boessenkool
2019-12-08 4:30 ` Frank Rowand
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