Date: Tue, 10 Oct 2017 10:47:30 +0800 From: Julian Elischer <julian@freebsd.org> To: Rick Macklem <rmacklem@uoguelph.ca>, Ian Lepore <ian@freebsd.org>, "freebsd-current@freebsd.org" <freebsd-current@freebsd.org> Subject: Re: RFC how to use kernel procs/threads efficiently Message-ID: <e4a4c6ff-5ce0-b979-ab84-32136acdcba6@freebsd.org> In-Reply-To: <YQXPR0101MB0997FAE97A7E42BCF570AA7EDD740@YQXPR0101MB0997.CANPRD01.PROD.OUTLOOK.COM> References: <YQXPR0101MB099752292CCAC9E8A72C1E96DD710@YQXPR0101MB0997.CANPRD01.PROD.OUTLOOK.COM> <1507317060.86205.268.camel@freebsd.org> <YQXPR0101MB0997FAE97A7E42BCF570AA7EDD740@YQXPR0101MB0997.CANPRD01.PROD.OUTLOOK.COM>
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On 10/10/17 4:25 am, Rick Macklem wrote: > ________________________________________ > Ian Lepore wrote: > [stuff snipped] >> taskqueue(9) is an existing mechanism to enqueue functions to execute >> asynch using a pool of threads, but it doesn't answer the scalability >> questions. In fact it may make them harder, inasmuch as I don't think >> there's a mechanism to dynamically adjust the number of threads after >> first calling taskqueue_start_threads(). > I've coded it using taskqueue and it seems to work ok. > The patch is here, in case anyone would like to review it: > https://www.reviews.freebsd.org/D12632 > > I don't know what the overheads are (or even how to measure/compare > them), but I suspect it is less than a kproc_create()/kproc_exit() for every > RPC. > > I also don't think having a fixed # of threads is a problem. Since NFS I/O > is so bursty, recent I/O activity doesn't give a good indication of how many > threads will be needed soon. In other words, it can go from no I/O to > heavy I/O and back to no I/O rapidly. > --> As such, having a fixed reasonable # of threads is probably the best > that can be done. > - The current patch has the # of threads as a sysctl with a default of 32. why not set it to ncpu or something? > > Thanks for your comments and feel free to review it, if you'd like, rick > _______________________________________________ > freebsd-current@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" >
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