Messages in this thread |  | | Date | Thu, 3 Aug 2017 19:14:29 +0200 | From | Guillaume Knispel <> | Subject | Re: [PATCH] ipc: optimize semget/shmget/msgget for lots of keys |
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On Wed, Aug 02, 2017 at 01:06:44PM -0700, Davidlohr Bueso wrote: > On Mon, 31 Jul 2017, Guillaume Knispel wrote: > >static int __init ipc_init(void) > >{ > >- sem_init(); > >- msg_init(); > >+ int err_sem, err_msg; > >+ > >+ err_sem = sem_init(); > >+ WARN(err_sem, "ipc: sysV sem_init failed: %d\n", err_sem); > >+ err_msg = msg_init(); > >+ WARN(err_msg, "ipc: sysV msg_init failed: %d\n", err_msg); > > shm_init(); > > This shows the ugliness of the underlying ipc init asymmetry. Specifically, > 140d0b2108f (Do 'shm_init_ns()' in an early pure_initcall) was the final > nail in the coffin to fix an exit_shm() race. > > While normally we could just initialize the ipc_ids fields statically and > be over with initcall dependencies, your patch will require inits be done > dynamically for the rhashtable_init(). Oh well. > > Also, why do you do this? > > >-pure_initcall(ipc_ns_init); > >+core_initcall(ipc_ns_init);
In linux/init.h I saw that a pure_initcall is reserved to only initialize variables and must have no dependency on anything else; I interpreted that, + "pure" in the name, thinking we should not e.g. allocate in a pure_initcall, however I see that net_ns_init() calls kmem_cache_create() and others, so maybe we can keep ipc_ns_init() as a pure_initcall?
Guillaume
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