Date: Sun, 4 Jul 2010 20:20:15 +0900 From: "Daisuke Aoyama" <aoyama@peach.ne.jp> To: "Alexander Motin" <mav@FreeBSD.org>, "FreeBSD-Current" <freebsd-current@freebsd.org> Subject: Re: [Need Help]isboot (iSCSI boot driver) version 0.2.1 Message-ID: <10CB692CA3FE4A8992B250B7F35B243B@ad.peach.ne.jp> In-Reply-To: <4C2F4B67.3060201@FreeBSD.org> References: <6BC2B2FBAFFA4C26A46977F121B707E1@ad.peach.ne.jp> <mailpost.1278162245.7916753.99842.mailing.freebsd.current@FreeBSD.cs.nctu.edu.tw> <4C2F4B67.3060201@FreeBSD.org>
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Hi, >> Notes/Known Issues/Limitations: >> FreeBSD can't use transfer length > 64KB. > > Since 8.0 FreeBSD can use any transfer lengths. 64K is a safety limit > for CAM SIMs that do not report maximum transfer size. If your driver > supports bigger transactions (and even if not), you should fill maxio > field in XPT_PATH_INQ response. I set maxio=1024*1024 in version 0.2.2. As a result, the request (each ccb) have 256 blocks (128KB). I don't know why it is 128KB. >> It seems CAM tag is used only 2 of 64 tags. >> I don't know a reason, but MAXPHYS limit? > > How many concurrent requests you are submitting? If you are testing it > with sequential read from file system - make sure you have sysctl > vfs.read_max set high enough. MAXPHYS does not affects number of > concurrent requests, only size of each one. I used vfs.read_max=32 and run only one dd. Now vfs.read_max=2048. I tried to run dd 4 times at background, then I got 4 x 30MB/s (read) and 4 x 21MB/s (write). Write is still slower than read, but it is enough. I can see 1 or 2 tags when reading, around 10 tags when writing. I guess that reading tag exists only for a short time. (or my execution order is not good) Thank you. Daisuke Aoyama
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