Path: ...!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: John Savard Newsgroups: comp.arch Subject: Re: Privilege Levels Below User Date: Tue, 11 Jun 2024 13:30:10 -0600 Organization: A noiseless patient Spider Lines: 14 Message-ID: <9b9h6jtuengblsscovsh7qc652lmao4vt8@4ax.com> References: <2024Jun9.185245@mips.complang.tuwien.ac.at> <38ob6jl9sl3ceb0qugaf26cbv8lk7hmdil@4ax.com> <2024Jun10.091648@mips.complang.tuwien.ac.at> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Date: Tue, 11 Jun 2024 21:30:11 +0200 (CEST) Injection-Info: dont-email.me; posting-host="f752231138247ec5b6f53ce61cda1d0c"; logging-data="1275443"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+hH7XB79IVMm4DRMhgLC0NASZ6fOK4ofo=" Cancel-Lock: sha1:V+dZZj1FbA/mcjxPgtd0XvvxsIc= X-Newsreader: Forte Free Agent 3.3/32.846 Bytes: 1867 On Tue, 11 Jun 2024 08:54:16 +0300, Niklas Holsti wrote: >Not always. If the mistakenly speculated cache-fetch /evicted/ some >other data from the (finite-sized) cache, and the evicted data are >needed later on the /true/ execution path, the mistakenly speculated >fetch has a /negative/ effect on performance. (This kind of "timing >anomaly" is very bothersome in static WCET analysis.) Ouch. Another argument for having a victim cache. And a benefit of doing it in what is apparently Mitch Alsup's way - holding off cache updates until instruction retirement. John Savard