Re: Linux does not care for data integrity

From: Bill Davidsen (davidsen_at_tmr.com)
Date: 06/02/05

  • Next message: Tony Lindgren: "[PATCH] Dynamic tick for x86 version 050602-1" 
    Date:	Wed, 01 Jun 2005 21:37:05 -0400
To: Jeff Garzik <jgarzik@pobox.com>

    Jeff Garzik wrote:

    > Bill Davidsen wrote:
    >
    >> This would change the meaning of fsync from "force out the data" to
    >> "wait for the data to be written" in some implementations.
    >
    >
    > This is the meaning of fsync: copies all in-core parts of a file to
    > disk, and waits until the device reports that all parts are on stable
    > storage.
    >
    > Anything less is a bug.

    How about anything more? The truth is that much common hardware doesn't
    really make the cache to disk move visible, and turning off cache really
    hurts performance. And it would appear that fsync force a lot more data
    out of memory than just the blocks for the file in question.

    However, the point I was making is that it would be useful to be able to
    tell when the write to non-volatile took place, not to force that to
    happen. Not to do anything which would flush a lot of other stuff and
    busy the drive. What I suggest is NOT fsync, just a way to assure ordering. 

    -- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979
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  • Next message: Tony Lindgren: "[PATCH] Dynamic tick for x86 version 050602-1"

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