Rusty Russell <[EMAIL PROTECTED]> writes:
> [This was part of the GDT cleanups and per-cpu-> pda changes, which I
> have revised, but this stands on its own. The only change is catching
> the x86-64 per-cpu allocator too].
> ==
> Let's allow page-alignment in general for per-cpu data (wanted by Xen,
> and Ingo suggested KVM as well).
>
> Because larger alignments can use more room, we increase the max
> per-cpu memory to 64k rather than 32k: it's getting a little tight.
>
> Signed-off-by: Rusty Russell <[EMAIL PROTECTED]>
> Acked-by: Ingo Molnar <[EMAIL PROTECTED]>
> ===================================================================
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -346,10 +346,10 @@ static void *percpu_modalloc(unsigned lo
> unsigned int i;
> void *ptr;
>
> - if (align > SMP_CACHE_BYTES) {
> - printk(KERN_WARNING "%s: per-cpu alignment %li > %i\n",
> - name, align, SMP_CACHE_BYTES);
> - align = SMP_CACHE_BYTES;
> + if (align > PAGE_SIZE) {
> + printk(KERN_WARNING "%s: per-cpu alignment %li > %li\n",
> + name, align, PAGE_SIZE);
> + align = PAGE_SIZE;
> }
>
> ptr = __per_cpu_start;
> @@ -430,7 +430,7 @@ static int percpu_modinit(void)
> pcpu_size = kmalloc(sizeof(pcpu_size[0]) * pcpu_num_allocated,
> GFP_KERNEL);
> /* Static in-kernel percpu data (used). */
> - pcpu_size[0] = -ALIGN(__per_cpu_end-__per_cpu_start, SMP_CACHE_BYTES);
> + pcpu_size[0] = -ALIGN(__per_cpu_end-__per_cpu_start, PAGE_SIZE);
> /* Free room. */
> pcpu_size[1] = PERCPU_ENOUGH_ROOM + pcpu_size[0];
> if (pcpu_size[1] < 0) {
Do we really want to allow modules to be able to allocate page sized
per cpu memory. If my memory servers on how this code works we will wind
up allocating 1 page of per cpu memory for every module that allocates a
per cpu variable. 128 bytes sucks 4k is an order of magnitude worse.
On x86_64 we are only reserving 8K for modules...
Eric
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