Re: [RFT] Support for ~2144 SCSI discs

[Mike Anderson <mike.anderson@us.ibm.com>]

Richard Gooch [rgooch@ras.ucalgary.ca] wrote:
> Jeremy Higdon writes:
> > With the sard patch and a 64 bit system, you start having
> > trouble at around 103 configured disks, because of the following
> 
> So even without my patch, sard doesn't support the previous limit of
> 128 devices.
> 
> > line in sd_init() (sd.c), because kmalloc doesn't like allocating
> > large chunks of memory:
> > 
> >         sd = kmalloc((sd_template.dev_max << 4) *
> >                                           sizeof(struct hd_struct),
> >                                           GFP_ATOMIC);
> > 
> > Without sard, you'd have problems past 512 disks.
> 
> Yes, when I was coding up the patch I noticed the use of GFP_ATOMIC in
> the allocation calls. I have two questions:
> - can we use GFP_KERNEL instead (why use GFP_ATOMIC)
> - can we switch to vmalloc() instead of kmalloc()?

In previous experiments trying to connect up to 512 devices we switched to
vmalloc because the static nature of sd.c's allocation exceeds 128k which
I assumed was the max for kmalloc YMMV.

> 				Regards,
> 
> 					Richard....
> Permanent: rgooch@atnf.csiro.au
> Current:   rgooch@ras.ucalgary.ca
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-Mike
-- 
Michael Anderson
mike.anderson@us.ibm.com