Am Montag, 17. September 2001 00:09 schrieben Sie:
> > > Hmm, added after 2.4.10pre2 ... :)
> >
> > Please explain.
> >
> > > Would you happen to have a pointer to more info about what
> > > this GFP_BUFFER flag is for
>
> "grep GFP_BUFFER include/linux/*.h" said nothing; <linux/mm.h>
> doesn't have such a mask. At least, in pre2.
You are right. I am afraid GFP_BUFFER was used only in 2.2 :-(
slab.h:#define SLAB_NOIO GFP_NOIO
This seems to be the way to do this in newer kernels.
Should I ask on linux-kernel ?
The issue is not clear as there is also a NOFS and I am not really sure about
the difference. And I am not sure how to use it ? GFP_KERNEL | GFP_NOIO ?
> > I have no exact pointer. It should be somewhere in the vm documentation.
> > Its meaning is "allocate memory without swapping" as opposed to ATOMIC's
> > taking memory from the free pages pool.
>
> OK, that's what I wanted to know. Modulo performance tweaking,
> it seems like it should only get used during swapping. (And drivers
> would need to be told that's the I/O mode.)
Sadly no. It applies to anything used to write out dirty pages.
Else there'd be the issue of reentry. The VM subsystem might decide to write
out another dirty page to the same device you are allocating memory for in
response to the request to write out the first page.
As you cannot know which scsi commands might be issued to prepare for a
write, you must allocate memory safely for any writeable block device.
Regards
Oliver
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