On Fri, 30 May 2008 08:01:02 +0200 Eric Dumazet <dada1@xxxxxxxxxxxxx> wrote: > Really, percpu allocations are currently not frequent at all. > > vmalloc()/vfreee() are way more frequent and still use a list. Sure it's hard to conceive how anyone could go and do a per-cpu allocation on a fastpath. But this has nothing to do with the frequency! The problems surround the _amount_ of allocated memory and the allocation/freeing patterns. Here's another example. And it's only an example! Generalise! ext3 maintains three percpu_counters per mount. Each percpu_counter does one percpu_alloc. People can mount an arbitrary number of ext3 filesystems! Another: there are two percpu_counters (and hence two percpu_alloc()s) per backing_dev_info. One backing_dev_info per disk and people have been known to have thousands (iirc ~10,000) disks online. And those examples were plucked only from today's kernel. Who knows what other problems will be in 2.6.45? -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
