Messages in this thread Patch in this message | | | Date | Tue, 5 Aug 2003 19:41:19 +0100 (BST) | From | Hugh Dickins <> | Subject | [PATCH] revert to static = {0} + comment |
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Please revert to static zero initialization of a const: when thus initialized it's linked into a readonly cacheline shared between cpus; otherwise it's linked into bss, likely to be in a dirty cacheline bouncing between cpus.
On 5 Aug 2003, Arjan van de Ven wrote: > how about adding a big fat comment here that says this? > Otherwise this keeps happening all the time... and others concurred.
Okay, by popular request, here it is with a small thin comment.
--- 2.6.0-test2-bk/mm/shmem.c Tue Aug 5 15:57:31 2003 +++ linux/mm/shmem.c Tue Aug 5 19:29:16 2003 @@ -296,7 +296,8 @@ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); struct page *page = NULL; swp_entry_t *entry; - static const swp_entry_t unswapped; + static const swp_entry_t unswapped = {0}; + /* = {0} to go in readonly data, to avoid bss cacheline bounce */ if (sgp != SGP_WRITE && ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) - 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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