Date: Wed, 8 Jan 2020 16:18:10 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Wojciech Puchar <wojtek@puchar.net> Cc: Gary Jennejohn <gljennjohn@gmail.com>, Hans Petter Selasky <hps@selasky.org>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Rick Macklem <rmacklem@uoguelph.ca> Subject: Re: maximum MAXBSIZE Message-ID: <20200108141810.GX23031@kib.kiev.ua> In-Reply-To: <alpine.BSF.2.20.2001081452360.44533@puchar.net> 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>
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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"
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