Messages in this thread | | | Date | Wed, 19 Oct 2011 19:17:18 -0700 | Subject | Re: Latency writing to an mlocked ext4 mapping | From | Andy Lutomirski <> |
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On Wed, Oct 19, 2011 at 6:15 PM, Andy Lutomirski <luto@amacapital.net> wrote: > On Wed, Oct 19, 2011 at 6:02 PM, Andreas Dilger <adilger@dilger.ca> wrote: >> What kernel are you using? A change to keep pages consistent during writeout was landed not too long ago (maybe Linux 3.0) in order to allow checksumming of the data. > > 3.0.6, with no relevant patches. (I have a one-liner added to the tcp > code that I'll submit sometime soon.) Would this explain the latency > in file_update_time or is that a separate issue? file_update_time > seems like a good thing to make fully asynchronous (especially if the > file in question is a fifo, but I've already moved my fifos to tmpfs).
On 2.6.39.4, I got one instance of:
call_rwsem_down_read_failed ext4_map_blocks ext4_da_get_block_prep __block_write_begin ext4_da_write_begin ext4_page_mkwrite do_wp_page handle_pte_fault handle_mm_fault do_page_fault page_fault
but I'm not seeing the large numbers of the ext4_page_mkwrite trace that I get on 3.0.6. file_update_time is now by far the dominant cause of latency.
I'll leave it running overnight and see what happens.
--Andy -- 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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