"David M. Grimes" wrote:
>
> All,
>
> I have just recently obtained, successfully built, and am experimenting with
> the kaio patches (1.3 for 2.4.0-test10). My questions are related to the
> use of raw devices with kaio, and specifically, to the comment on the KAIO
> homepage which says:
>
> "KAIO is also integrated to work well with Raw I/O, another
> feature availabe with SGI Linux Environment 1.1 or as a patch
> from this web site."
>
> I could only find the Raw I/O (SCSI SGI patches) for 2.2.13, and 2.4.0+ has
> the Tweedie char/raw.c raw devices by default. So, are the SGI patches
> integrated in another set of patches? Is the native stuff as good now, and
> the patches are no longer being maintained? If not, can they be made
> available so they are suitable for the same kernel version as kaio?
That comment really applies to 2.2 kernels ... that
SGI raw i/o patch was written in days when raw i/o
was not fully available in linux. Stephen Tweedie's
raw I/O is now part of 2.4 as you noted.
The 2.4 raw i/o, however, does not provide seperate
inititate_io and wait_io functions. Thus, the number
of outstanding raw i/o will be limited by the number
of slave threads. Also, the 2.4 raw I/O uses bufferheads
to queue the I/O as compared the SGI SCSI patch which
directly translates the I/O into a scsi scatter-gather list.
The SGI SCSI patch is not available for 2.4 ...
hope this helps!
ananth.
--------------------------------------------------------------------------
Rajagopal Ananthanarayanan ("ananth")
Member Technical Staff, SGI.
--------------------------------------------------------------------------
|