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[91.59.224.142]) by smtp.gmail.com with ESMTPSA id q14sm3172237wmj.14.2020.01.08.01.51.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jan 2020 01:51:38 -0800 (PST) Date: Wed, 8 Jan 2020 10:51:36 +0100 From: Gary Jennejohn To: Rick Macklem Cc: Hans Petter Selasky , Wojciech Puchar , "freebsd-hackers@freebsd.org" Subject: Re: maximum MAXBSIZE Message-ID: <20200108105136.0d54ebce@ernst.home> In-Reply-To: References: Reply-To: gljennjohn@gmail.com X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; amd64-portbld-freebsd13.0) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 47t4Js0dSVz4JCr X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=qxsIllXx; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of gljennjohn@gmail.com designates 2a00:1450:4864:20::42a as permitted sender) smtp.mailfrom=gljennjohn@gmail.com X-Spamd-Result: default: False [-3.00 / 15.00]; TO_DN_EQ_ADDR_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; HAS_REPLYTO(0.00)[gljennjohn@gmail.com]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36]; FREEMAIL_FROM(0.00)[gmail.com]; REPLYTO_ADDR_EQ_FROM(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; DKIM_TRACE(0.00)[gmail.com:+]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; RECEIVED_SPAMHAUS_PBL(0.00)[142.224.59.91.khpj7ygk5idzvmvt5x4ziurxhy.zen.dq.spamhaus.net : 127.0.0.10]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; DWL_DNSWL_NONE(0.00)[gmail.com.dwl.dnswl.org : 127.0.5.0]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[text/plain]; FREEMAIL_REPLYTO(0.00)[gmail.com]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; IP_SCORE_FREEMAIL(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[a.2.4.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.5.4.1.0.0.a.2.list.dnswl.org : 127.0.5.0]; IP_SCORE(0.00)[ip: (-9.30), ipnet: 2a00:1450::/32(-2.61), asn: 15169(-1.85), country: US(-0.05)]; RCVD_TLS_ALL(0.00)[] X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 08 Jan 2020 09:51:42 -0000 On Tue, 7 Jan 2020 22:47:54 +0000 Rick Macklem 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