Messages in this thread | | | Subject | Re: [PATCH] kmalloc_percpu | From | "David S. Miller" <> | Date | 06 May 2003 02:23:20 -0700 |
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On Tue, 2003-05-06 at 01:03, Rusty Russell wrote: > And #3 is, in fact, the one I care about. The extra memory reference > is already probably cachehot (all static per-cpu use it), and might be > in a register on some archs. > > Doesn't break with sparce CPU #s, but yes, it is inefficient.
Maybe we should treat this stuff like architecture ABIs that have a "small data" section?
Before elaborating, let me state that if we are going to use this for things like disk stats and per-interface ipv6 ICMP stats, a fixed size pool is absolutely unacceptable. People are configuring up thousands upon thousands of VLAN net devices today, and if IPV6 is enabled each of those will get a per-cpu ICMP stats block allocated. And as Andrew said, there can be thousands of block devices.
Therefore, for these per-cpu applications there must be no limits built into the mechanism.
Now, what I propose is that kmalloc_percpu() keeps it's current implementation. Then we have a kmalloc_percpu_small() that must only be invoked during module init and we limit the size to some reasonable amount. This kmalloc_percpu_small() uses the 32K pool or whatever, as does DECLARE_PERCPU in a module.
How about this?
-- David S. Miller <davem@redhat.com> - 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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