Re: Blkparse weirdness with "A" (remap) action

[Jens Axboe <jens.axboe@oracle.com>]

On Fri, Jul 27 2007, Paul P Komkoff Jr wrote:
> Replying to Paul P Komkoff Jr:
> > I'm having a little problem here. I have a setup with md over some
> > disks, and I'm running blktrace /dev/md? /dev/sd?, then doing blkparse
> > *.blktrace.*, I'm getting this kind of stuff:
> > 
> >  40,131071  1       67     3.043450168   420  A   W 4274944 + 8 <- (253,0) 4275328
> >  40,131071  1       67     3.043450168   420  A   W 4274944 + 8 <- (253,0) 4275328
> 
> Replying to my own message.
> I assume this is because we have this in kernel:
> 
> /*
>  * The remap event
>  */
> struct blk_io_trace_remap {
>         __be32 device;
>         u32 __pad;
>         __be64 sector;
> };
> 
> but this in blktrace:
> 
> /*
>  * The remap event
>  */
> struct blk_io_trace_remap {
>         __u32 device;
>         __u32 device_from;
>         __u64 sector;
> };

I think Alan had a patch for filling in that missing device_from value,
currently it's not used in the kernel (as you spotted). Alan?

-- 
Jens Axboe