At 08:42 11/06/02, Andrew Morton wrote:
>Rusty Russell wrote:
> >
> > Linus, please apply. Tested on my dual x86 box.
> >
> > This patch removes smp_num_cpus, cpu_number_map and cpu_logical_map
> > from generic code, and uses cpu_online(cpu) instead, in preparation
> > for hotplug CPUS.
>
>umm. This patch does introduce a non-zero amount of bloat:
>
> > ...
> > - ntfs_compression_buffers = (u8**)kmalloc(smp_num_cpus *
> sizeof(u8*),
> > + ntfs_compression_buffers = (u8**)kmalloc(NR_CPUS * sizeof(u8*),
This is crazy! It means you are allocating 2MiB of memory instead of just
128kiB on a 2 CPU system, which will be about 99% of the SMP systems in
use, at my guess. So your change is throwing away 1920kiB of kernel ram for
no reason at all. And that is just ntfs...
CPU hot plugging is an extremely specialised corner case so can you please
make it a config option and not get rid of smp_num_cpus? If people enable
the option make smp_num_cpus be the same as NR_CPUS and if not leave it be
as it is now.
Anything else penalizes the majority of users just to allow a tiny minority
to do strange things like swap cpus without rebooting...
Anton
-- "I've not lost my mind. It's backed up on tape somewhere." - Unknown -- Anton Altaparmakov <aia21 at cantab.net> (replace at with @) Linux NTFS Maintainer / IRC: #ntfs on irc.openprojects.net WWW: http://linux-ntfs.sf.net/ & http://www-stu.christs.cam.ac.uk/~aia21/- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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