Date: Tue, 10 Nov 1998 20:54:05 -0800 (PST) From: Julian Elischer <julian@whistle.com> To: Greg Lehey <grog@lemis.com> Cc: Peter Jeremy <peter.jeremy@auss2.alcatel.com.au>, hackers@FreeBSD.ORG Subject: Re: SCSI tagged queueing and softupdates Message-ID: <Pine.BSF.3.95.981110205112.15329I-100000@current1.whistle.com> In-Reply-To: <19981111151628.J20374@freebie.lemis.com>
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On Wed, 11 Nov 1998, Greg Lehey wrote: > On Tuesday, 10 November 1998 at 20:16:08 -0800, Julian Elischer wrote: > > > Soft updates will not schedule any IO that depends on an uncompleted IO > > operation. So therefore all operations that have been 'passed to the > > driver' are not dependent on each other (by definition) > > Doesn't this slow the whole thing down? Or is that what's behind > B_ORDERED? Softupdates doesn't use B_ORDERED no, it can write out a directory block even if there are uncompleted inode writes it is waiting on... it fabricates a directory block with those entries, marked as invalid and writes out that copy instead. When the inode writes are completed, it will schedule a rewrite to the disk of the completed block. it's incredibally sneaky that way.. same for inodes. etc. > > Greg > -- > See complete headers for address, home page and phone numbers > finger grog@lemis.com for PGP public key > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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