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Hermes SMTP Server) with ESMTPA ID 4fb6de71de49ceb5d6cfe8b7952df3db; Wed, 10 May 2023 02:20:05 +0000 (UTC) From: Mark Millard Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3731.400.51.1.1\)) Subject: Cores of different performance vs. time spent creating threads: Windows Dev Kit 2023 example Message-Id: <11EBAA22-6E0F-4B27-9799-7786E149D9B1@yahoo.com> Date: Tue, 9 May 2023 19:19:53 -0700 Cc: freebsd-arm To: FreeBSD Hackers X-Mailer: Apple Mail (2.3731.400.51.1.1) References: <11EBAA22-6E0F-4B27-9799-7786E149D9B1.ref@yahoo.com> X-Spamd-Result: default: False [-1.82 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-0.997]; NEURAL_SPAM_SHORT(0.68)[0.682]; MV_CASE(0.50)[]; DMARC_POLICY_ALLOW(-0.50)[yahoo.com,reject]; R_DKIM_ALLOW(-0.20)[yahoo.com:s=s2048]; R_SPF_ALLOW(-0.20)[+ptr:yahoo.com]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; DWL_DNSWL_NONE(0.00)[yahoo.com:dkim]; RCVD_IN_DNSWL_NONE(0.00)[98.137.66.147:from]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_LAST(0.00)[]; ASN(0.00)[asn:36647, ipnet:98.137.64.0/20, country:US]; TO_DN_ALL(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; FREEMAIL_FROM(0.00)[yahoo.com]; MLMMJ_DEST(0.00)[freebsd-hackers@freebsd.org]; DKIM_TRACE(0.00)[yahoo.com:+]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; FREEMAIL_ENVFROM(0.00)[yahoo.com]; MIME_TRACE(0.00)[0:+]; RWL_MAILSPIKE_POSSIBLE(0.00)[98.137.66.147:from] X-Rspamd-Queue-Id: 4QGJdk6wM6z3wR5 X-Spamd-Bar: - X-ThisMailContainsUnwantedMimeParts: N First some context that reaches an oddity that seems to be involved in the time to create threads . . . The Windows Dev Kit 2023 (WDK23 abbrevation here) boot reports: CPUs (cores) 0..3: cortex-a78c (the slower cores) CPUs (cores) 4..7: cortex-x1c (the faster cores) Building a kernel explicitly via involving -mcpu= use gets the following oddity relative to cpu numbering when the kernel is used: -mcpu=cortex-x1c or -mcpu=cortex-a78c: Benchmarking tracks that number/performance pairing. -mcpu=cortex-a72: The slower vs. faster gets swapped number blocks. So, for -mcpu=cortex-a72 , 0..3 are the faster cores. This sets up for the following . . . But I also observe (a relative comparison of contexts via some benchmark-like activity): -mcpu=cortex-x1c or -mcpu=cortex-a78c based kernel: threads take more time to create -mcpu=cortex-a72 based kernel: threads take less time to create The difference is not trivial for the activity involved for this WDK23 context. If there is a bias as to which core(s) are involved in part of thread creation generally, it would appear to be important that the bias to be to the more performant cores (for what the activity involves). The above suggests that such is possibly not necessarily the case for FreeBSD as is. BIG/little (and analogous?) cause this to become more relevant. Does this hypothesis about what type of thing is going on fit with how FreeBSD actually works? As stands, I'm going to experiment with the WDK23 using a cortex-a72 targeted kernel but a cortex-x1c/cortex-a78c targeted world for my general operation of the WDK23. Note: While the benchmark results allow seeing in plots what traces back to thread creation time contributions, the benchmark itself does not directly measure that time. It is more like, the average work rate for a time changes based on the fraction of the time involved in the thread creations for each given problem size. The actual definition of work here involves a mathematical quantity for a mathematical problem (that need not be limited to computers doing the work). The benchmark results are more useful for discovering that there is something to potentially investigate than to actually do an investigation with. === Mark Millard marklmi at yahoo.com