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[209.85.166.41]) by smtp.gmail.com with ESMTPSA id z20sm10062742iof.38.2019.09.07.18.58.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 07 Sep 2019 18:58:24 -0700 (PDT) Received: by mail-io1-f41.google.com with SMTP id r4so21242838iop.4; Sat, 07 Sep 2019 18:58:24 -0700 (PDT) X-Received: by 2002:a02:cb51:: with SMTP id k17mr17624889jap.119.1567907904477; Sat, 07 Sep 2019 18:58:24 -0700 (PDT) MIME-Version: 1.0 References: <201909060119.x861JWrG006910@repo.freebsd.org> <4917d7507b6ea6c360dccda261f53052aa085f2b.camel@freebsd.org> <5EE266EE-E650-48D8-9B0E-E674AD026470@freebsd.org> <3cb6429acc7e520932d2c906d1cac47540156355.camel@freebsd.org> <8F03EA29-0F3F-4321-9241-78F7C924FDE1@freebsd.org> <9BC03B61-F8B5-476C-AD34-9DEA5230BFCF@freebsd.org> In-Reply-To: Reply-To: cem@freebsd.org From: Conrad Meyer Date: Sat, 7 Sep 2019 18:58:13 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: What value HZ? To: "Constantine A. Murenin" Cc: "freebsd-arch@freebsd.org" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 46Qvb66gzyz4M96 X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of csecem@gmail.com designates 209.85.166.68 as permitted sender) smtp.mailfrom=csecem@gmail.com X-Spamd-Result: default: False [-3.65 / 15.00]; TO_DN_EQ_ADDR_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; HAS_REPLYTO(0.00)[cem@freebsd.org]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip4:209.85.128.0/17]; REPLYTO_ADDR_EQ_FROM(0.00)[]; RCVD_COUNT_THREE(0.00)[4]; NEURAL_HAM_SHORT(-0.99)[-0.986,0]; RCPT_COUNT_TWO(0.00)[2]; FORGED_SENDER(0.30)[cem@freebsd.org,csecem@gmail.com]; SUBJECT_ENDS_QUESTION(1.00)[]; R_DKIM_NA(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; FROM_NEQ_ENVFROM(0.00)[cem@freebsd.org,csecem@gmail.com]; TAGGED_FROM(0.00)[]; ASN(0.00)[asn:15169, ipnet:209.85.128.0/17, country:US]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; TAGGED_RCPT(0.00)[]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[freebsd.org]; MIME_TRACE(0.00)[0:+]; RCVD_IN_DNSWL_NONE(0.00)[68.166.85.209.list.dnswl.org : 127.0.5.0]; IP_SCORE(-1.66)[ip: (-2.68), ipnet: 209.85.128.0/17(-3.32), asn: 15169(-2.27), country: US(-0.05)]; RWL_MAILSPIKE_POSSIBLE(0.00)[68.166.85.209.rep.mailspike.net : 127.0.0.17]; RCVD_TLS_ALL(0.00)[] X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 08 Sep 2019 01:58:28 -0000 Hi Constantine, On Sat, Sep 7, 2019 at 3:05 PM Constantine A. Murenin wrote: > > For the sake of discussion, I recall that there was a measurable power > consumption difference between FreeBSD (HZ=3D1000) and OpenBSD (HZ=3D100)= when > I played with a Kill-A-Watt a number of years ago. Unfortunately, this is an apples to oranges comparison, and perhaps worse, vague and dated. It would be more interesting to compare HZ=3D1000 to HZ=3D100 with an otherwise identical CURRENT FreeBSD system. As far as I can tell, FreeBSD grew "tickless" timer support in r212541 in 2010 (thanks mav@). This is easily observed on my idle HZ=3D1000 amd64 system with 'vmstat -i': "cpu0:timer" is firing at an average rate of 21 Hz =E2=80=94 not 1000. And that is the most frequent interrupt. > Would it perhaps be prudent to try to qualify whether, and by how much, > this change affects power consumption on MIPS/ARM/RISCV, not just whether > each arch could cope with the change? If someone has the time and inclination, then of course, it could be an interesting test to run. Best, Conrad