Messages in this thread |  | | | Date | Tue, 11 Jun 2002 15:54:09 +0100 | | From | Anton Altaparmakov <> | | Subject | Re: [PATCH] 2.5.21 Nonlinear CPU support |
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At 20:29 11/06/02, Denis Vlasenko wrote: >On 11 June 2002 08:57, Anton Altaparmakov wrote: > > 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... > >Wait a minute. >These buffers are allocated per CPU. Can we allocate additional ones when >new CPU is added?
Of course, see my suggestion for how to handle this in the post after the one you replied to.
>I do hope these buffers aren't allocated an boot time but at mount time, >are they?
At mount time and only if the volume supports compression. And they are ntfs global, i.e. not per mount point. That is still a big ram waste.
>I'm sorry it sounds like NTFS code needs rework, not Rusty's patch.
Sorry to disappoint you but my code is as efficient as possible while NR_CPUs is as ugly and inefficient as hell.
>Feel free to enlighten me why I am wrong.
I hope I have managed to do that. (-:
Best regards,
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/
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