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Date: Wed, 28 Mar 2007 02:45:23 -0400 From: "Xin Zhao" <uszhaoxin@...il.com> To: linux-kernel <linux-kernel@...r.kernel.org>, linux-fsdevel <linux-fsdevel@...r.kernel.org>, "Xin Zhao" <uszhaoxin@...il.com> Subject: Linux page cache issue? Hi, If a Linux process opens and reads a file A, then it closes the file. Will Linux keep the file A's data in cache for a while in case another process opens and reads the same in a short time? I think that is what I heard before. But after I digged into the kernel code, I am confused. When a process closes the file A, iput() will be called, which in turn calls the follows two functions: iput_final()->generic_drop_inode() But from the following calling chain, we can see that file close will eventually lead to evict and free all cached pages. Actually in truncate_complete_page(), the pages will be freed. This seems to imply that Linux has to re-read the same data from disk even if another process B read the same file right after process A closes the file. That does not make sense to me. /***calling chain ***/ generic_delete_inode/generic_forget_inode()-> truncate_inode_pages()->truncate_inode_pages_range()-> truncate_complete_page()->remove_from_page_cache()-> __remove_from_page_cache()->radix_tree_delete() Am I missing something? Can someone please provide some advise? Thanks a lot -x - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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