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On Wed, 9 Aug 2006 22:13:27 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote: > On Thu, 10 Aug 2006, KAMEZAWA Hiroyuki wrote: > > > > There is no freelist for slabs. slabs are immediately returned to the page > > > allocator. The page allocator has its own per cpu page queues that should provide > > > enough caching. > > > > > > > I think that the advantage of Slab allocator is > > - object is already initizalized at setup, so you don't have to initialize it again at > > allocation. > > - object is initialized only once when slab is created. > > If you do that then you loose the cache hot advantage. It is advantageous > to initialize the object and then immediately use it. If you initialize it > before then the cacheline will be evicted and then brought back. hmm, I don't know precise analization of the perfromance benefit of slab on current (Linux + Fast CPU/Bus + Large Cache) systems. I'm grad if you show the performance of new "Simple Slab" next time. > > > If a slab page is returned to page allocator ASAP, # of object initilization may > > increase. > > The initializers in the existing slab are only used in rare cases in the > kernel. > > Because of inode_init_once, many codes which uses inode uses initilization code. And inode is one of heavy users of slab. [kamezawa@aworks linux-2.6.18-rc4]$ grep init_once /proc/kallsyms c0155cdf t init_once c0163e00 t init_once c016ef02 t init_once c0172a01 T inode_init_once c0172b77 t init_once c0187704 t init_once c019a19f t init_once c01aa643 t init_once c01abd3f t init_once c01acdab t init_once c01b2500 t init_once c01d3139 t init_once c01db8b3 t init_once c02f9a62 t init_once c0358ab5 t init_once c03b9f6c r __ksymtab_inode_init_once c03c28fe r __kstrtab_inode_init_once performance measurement related to inode will show good data. maybe Thanks, - Kame - 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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