Date: Sun, 30 Oct 2005 18:00:24 +0800 From: David Xu <davidxu@freebsd.org> To: freebsd-current@freebsd.org Cc: Alexander Leidinger <Alexander@Leidinger.net> Subject: Re: TSC instead of ACPI: powerd doesn't work anymore (to be expected?) Message-ID: <436499B8.8000304@freebsd.org> In-Reply-To: <20051030093718.GE39253@dragon.NUXI.org> References: <30595.1130493297@critter.freebsd.dk> <20051028153457.d0wqgn2ask4sgw4k@netchild.homeip.net> <20051029195703.GB39253@dragon.NUXI.org> <43646AAC.2080107@freebsd.org> <20051030093718.GE39253@dragon.NUXI.org>
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David O'Brien wrote: >>TSC is faster than any others, on many systems, so-called ACPI-fast >>timer is really a slow chip, >> >> > >Correct, but why is it felt the latency of the ACPI timer is an issue? >Of course we all want things to as fast as possible, but is that just an >abstract desire, or a real issue was run into? > > > mysql benchmark - supersmack already told us this is an issue, this is the reason why mysql runs slower on FreeBSD than on Linux: ACPI-fast timecounter: alona# super-smack ./select-key-local.smack 10 1000 Query Barrel Report for client smacker1 connect: max=4ms min=3ms avg= 3ms from 10 clients Query_type num_queries max_time min_time q_per_s select_index 20000 1 0 7210.39 TSC timecounter: alona# super-smack ./select-key-local.smack 10 1000 Query Barrel Report for client smacker1 connect: max=3ms min=2ms avg= 2ms from 10 clients Query_type num_queries max_time min_time q_per_s select_index 20000 0 0 9301.19
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