Date: Thu, 9 Jan 2020 09:14:47 -0700 From: Warner Losh <imp@bsdimp.com> To: Gary Jennejohn <gljennjohn@gmail.com> Cc: Wojciech Puchar <wojtek@puchar.net>, Hans Petter Selasky <hps@selasky.org>, Rick Macklem <rmacklem@uoguelph.ca>, Conrad Meyer <cem@freebsd.org>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Konstantin Belousov <kostikbel@gmail.com> Subject: Re: maximum MAXBSIZE Message-ID: <CANCZdfqwMFGV3DAsR1skbjrZL2WgSMOR5L=zpscjGCSSTKS7Bg@mail.gmail.com> In-Reply-To: <20200109164519.33fc7478@ernst.home> References: <alpine.BSF.2.20.2001072210410.21107@puchar.net> <d79078c4-f1cb-93b9-ee6e-f689936c1e01@selasky.org> <YQBPR0101MB1427EEDE94AA6E34B49C3C09DD3F0@YQBPR0101MB1427.CANPRD01.PROD.OUTLOOK.COM> <20200108105136.0d54ebce@ernst.home> <alpine.BSF.2.20.2001081452360.44533@puchar.net> <20200108141810.GX23031@kib.kiev.ua> <CAG6CVpUrGyov12nQSKhofCPw5fAiXgDGChxf3-aFu1fKpirJTQ@mail.gmail.com> <alpine.BSF.2.20.2001091057420.96836@puchar.net> <CANCZdfokuE%2BKheFvSnx7M4he9Drx31xLj8o_GKUGJqKk32Oj7g@mail.gmail.com> <alpine.BSF.2.20.2001091520120.10661@puchar.net> <20200109164519.33fc7478@ernst.home>
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On Thu, Jan 9, 2020 at 8:45 AM Gary Jennejohn <gljennjohn@gmail.com> wrote: > On Thu, 9 Jan 2020 15:21:25 +0100 (CET) > Wojciech Puchar <wojtek@puchar.net> wrote: > > > why FreeBSD default is so completely wrong for modern hardware? > > > > i think 4MB is OK for HDDs, more may be optimal for RAID5 arrays. > > > > POLA (principle of least amazement). I certainly don't need a MAXPHYS set > to 4MB on my desktop machine. Not everyone using FreeBSD is running > servers with large amounts of memory and disk storage. > > It's a trivial change if it's beneficial in a certain use scenario. The > decision should be left up to the user. > And if you change MAXPHYS, you'll also want to bump the insanely small runningbuf limits. And there may be a few other parameters I've not reported that we set that are critical too :) Warner > > > > On Thu, 9 Jan 2020, Warner Losh wrote: > > > > > Netflix runs our entire network at MAXPHYS=8MB since we're doing huge > reads off HDD. > > > Warner > > > > > > > > > On Thu, Jan 9, 2020 at 2:58 AM Wojciech Puchar <wojtek@puchar.net> > wrote: > > > 2MB MAXPHYS was what i have set for over 3 years without > problems. > > > > > > On Wed, 8 Jan 2020, Conrad Meyer wrote: > > > > > > > Bufs are dynamically allocated from uma now, and perhaps a > middle ground BSIZE is worth considering? Would 1MB and 2kB > > > bufs (1kB > > > > 32-bit) be awful? > > > > > > > > Cheers, > > > > Conrad__ > > > > > > > > On Wed, Jan 8, 2020 at 06:18 Konstantin Belousov < > kostikbel@gmail.com> wrote: > > > >__ __ __ __On Wed, Jan 08, 2020 at 02:52:57PM +0100, Wojciech > Puchar wrote: > > > >__ __ __ __> sorry i made a mistake - i change MAXPHYS not > MAXBSIZE. > > > >__ __ __ __> > > > >__ __ __ __> 16MB works for now without problems > > > >__ __ __ __MAXPHYS 16MB means that sizeof(struct buf) is around > 32K (16K on 32bit). > > > > > > > >__ __ __ __> > > > >__ __ __ __> On Wed, 8 Jan 2020, Gary Jennejohn wrote: > > > >__ __ __ __> > > > >__ __ __ __> > On Tue, 7 Jan 2020 22:47:54 +0000 > > > >__ __ __ __> > Rick Macklem <rmacklem@uoguelph.ca> wrote: > > > >__ __ __ __> > > > > >__ __ __ __> > > Hans Petter Selasky wrote: > > > >__ __ __ __> > > > On 2020-01-07 22:12, Wojciech Puchar wrote: > > > >__ __ __ __> > > > > default MAXBSIZE is 128kB. badly low for > todays magnetic disks. > > > >__ __ __ __> > > > > > > > >__ __ __ __> > > > > i have it set to 2MB on all computers that > have magnetic disks. Great > > > >__ __ __ __> > > > > improvement with large files. especially > when more than one are > > > >__ __ __ __> > > > > read/wrote in parallel. And no problems > experienced > > > >__ __ __ __> > > > > > > > >__ __ __ __> > > > > But for optimal performance MAXBSIZE > should be transfered in few times > > > >__ __ __ __> > > > > longer than average seek time. todays disk > do 200-250MB/s so 2MB is > > > >__ __ __ __> > > > > transfered below 10ms. > > > >__ __ __ __> > > > > > > > >__ __ __ __> > > > > 8-16MB seems like good choice. is there > any reason not to set it that high? > > > >__ __ __ __> > > > > > > >__ __ __ __> > > > Old disk may not support it, especially USB > 1.0/2.0 disks. > > > >__ __ __ __> > > I also thought it was limited to MAXPHYS, but > maybe I'm only thinking of the NFS > > > >__ __ __ __> > > specific case? > > > >__ __ __ __> > > > > > >__ __ __ __> > > > > >__ __ __ __> > There's a comment in param.h that it should not > exceed MAXPHYS to be > > > >__ __ __ __> > on the safe side.__ How old that comment is I > can't say and that may > > > >__ __ __ __> > not be the case today. > > > >__ __ __ __> > > > > >__ __ __ __> > MAXBSIZE is only 64KiB in my param.h. > > > >__ __ __ __> > > > > >__ __ __ __> > I have to agree with HPS.__ There are many old > bridge-chips still in > > > >__ __ __ __> > use and problems with a large MAXBSIZE might > occur.__ It's certainly > > > >__ __ __ __> > not uncommon to see capacity limitations - I > have a docking station > > > >__ __ __ __> > which can't see more than 3TB. > > > >__ __ __ __> > > > > >__ __ __ __> > -- > > > >__ __ __ __> > Gary Jennejohn > > > >__ __ __ __> > > > > >__ __ __ __> > > > > >__ __ __ __> _______________________________________________ > > > >__ __ __ __> freebsd-hackers@freebsd.org mailing list > > > >__ __ __ __> > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > > >__ __ __ __> To unsubscribe, send any mail to " > freebsd-hackers-unsubscribe@freebsd.org" > > > >__ __ __ _________________________________________________ > > > >__ __ __ __freebsd-hackers@freebsd.org mailing list > > > >__ __ __ __ > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > > >__ __ __ __To unsubscribe, send any mail to " > freebsd-hackers-unsubscribe@freebsd.org" > > > > > > > > > > > > > > > _______________________________________________ > > > freebsd-hackers@freebsd.org mailing list > > > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > > To unsubscribe, send any mail to " > freebsd-hackers-unsubscribe@freebsd.org" > > > > > > > > > > > _______________________________________________ > > freebsd-hackers@freebsd.org mailing list > > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > To unsubscribe, send any mail to " > freebsd-hackers-unsubscribe@freebsd.org" > > > -- > Gary Jennejohn >
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