[PATCH 04/10] Use percpu buffers

Pekka Enberg penberg at kernel.org
Mon Aug 9 18:57:42 UTC 2010


On Mon, Aug 9, 2010 at 8:26 PM, Nitin Gupta <ngupta at vflare.org> wrote:
> @@ -303,38 +307,41 @@ static int zram_write(struct zram *zram, struct bio *bio)
>                                zram_test_flag(zram, index, ZRAM_ZERO))
>                        zram_free_page(zram, index);
>
> -               mutex_lock(&zram->lock);
> +               preempt_disable();
> +               zbuffer = __get_cpu_var(compress_buffer);
> +               zworkmem = __get_cpu_var(compress_workmem);
> +               if (unlikely(!zbuffer || !zworkmem)) {
> +                       preempt_enable();
> +                       goto out;
> +               }

The per-CPU buffer thing with this preempt_disable() trickery looks
overkill to me. Most block device drivers seem to use mempool_alloc()
for this sort of thing. Is there some reason you can't use that here?



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