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From: Florian Weimer <fweimer@redhat.com>
To: Noah Goldstein via Libc-alpha <libc-alpha@sourceware.org>
Cc: Noah Goldstein <goldstein.w.n@gmail.com>,
	 hjl.tools@gmail.com, carlos@systemhalted.org
Subject: Re: [PATCH v1] x86: Use 64MB as nt-store threshold if no cacheinfo [BZ #30429]
Date: Tue, 09 May 2023 10:56:29 +0200	[thread overview]
Message-ID: <87wn1h6fya.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <20230509031020.3496291-1-goldstein.w.n@gmail.com> (Noah Goldstein via Libc-alpha's message of "Mon, 8 May 2023 22:10:20 -0500")

* Noah Goldstein via Libc-alpha:

> If `non_temporal_threshold` is below `minimum_non_temporal_threshold`,
> it almost certainly means we failed to read the systems cache info.
>
> In this case, rather than defaulting the minimum correct value, we
> should default to a value that gets at least reasonable
> performance. 64MB is chosen conservatively to be at the very high
> end. This should never cause non-temporal stores when, if we had read
> cache info, we wouldn't have otherwise.

I think that's quite surprising for GLIBC_TUNABLES.  Maybe that logic
should only activate if the default was set from cache sizes?

Thanks,
Florian


  reply	other threads:[~2023-05-09  8:56 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-09  3:10 Noah Goldstein
2023-05-09  8:56 ` Florian Weimer [this message]
2023-05-09 16:01   ` Noah Goldstein
2023-05-11 18:15     ` Noah Goldstein
2023-05-25  8:11     ` Florian Weimer
2023-05-25 18:36 ` H.J. Lu
2023-06-05 17:14 ` Noah Goldstein
2023-06-05 17:45   ` H.J. Lu
2023-06-05 20:28     ` Noah Goldstein

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