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  1. 01 May, 2006 5 commits
    • Jens Axboe's avatar
      [PATCH] pipe: enable atomic copying of pipe data to/from user space · f6762b7a
      Jens Axboe authored 
      The pipe ->map() method uses kmap() to virtually map the pages, which
is both slow and has known scalability issues on SMP. This patch enables
atomic copying of pipe pages, by pre-faulting data and using kmap_atomic()
instead.

lmbench bw_pipe and lat_pipe measurements agree this is a Good Thing. Here
are results from that on a UP machine with highmem (1.5GiB of RAM), running
first a UP kernel, SMP kernel, and SMP kernel patched.

Vanilla-UP:
Pipe bandwidth: 1622.28 MB/sec
Pipe bandwidth: 1610.59 MB/sec
Pipe bandwidth: 1608.30 MB/sec
Pipe latency: 7.3275 microseconds
Pipe latency: 7.2995 microseconds
Pipe latency: 7.3097 microseconds

Vanilla-SMP:
Pipe bandwidth: 1382.19 MB/sec
Pipe bandwidth: 1317.27 MB/sec
Pipe bandwidth: 1355.61 MB/sec
Pipe latency: 9.6402 microseconds
Pipe latency: 9.6696 microseconds
Pipe latency: 9.6153 microseconds

Patched-SMP:
Pipe bandwidth: 1578.70 MB/sec
Pipe bandwidth: 1579.95 MB/sec
Pipe bandwidth: 1578.63 MB/sec
Pipe latency: 9.1654 microseconds
Pipe latency: 9.2266 microseconds
Pipe latency: 9.1527 microseconds
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
      f6762b7a
    • Jens Axboe's avatar
      [PATCH] splice: call handle_ra_miss() on failure to lookup page · e27dedd8
      Jens Axboe authored 
      Notify the readahead logic of the missing page. Suggested by
Oleg Nesterov.
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
      e27dedd8
    • Jens Axboe's avatar
      [PATCH] Add ->splice_read/splice_write to def_blk_fops · 7f9c51f0
      Jens Axboe authored 
      It can use the generic handlers.
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
      7f9c51f0
    • Jens Axboe's avatar
      [PATCH] pipe: introduce ->pin() buffer operation · f84d7519
      Jens Axboe authored 
      The ->map() function is really expensive on highmem machines right now,
since it has to use the slower kmap() instead of kmap_atomic(). Splice
rarely needs to access the virtual address of a page, so it's a waste
of time doing it.

Introduce ->pin() to take over the responsibility of making sure the
page data is valid. ->map() is then reduced to just kmap(). That way we
can also share a most of the pipe buffer ops between pipe.c and splice.c
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
      f84d7519
    • Jens Axboe's avatar
      [PATCH] splice: fix bugs in pipe_to_file() · 0568b409
      Jens Axboe authored 
      Found by Oleg Nesterov <oleg@tv-sign.ru>, fixed by me.

- Only allow full pages to go to the page cache.
- Check page != buf->page instead of using PIPE_BUF_FLAG_STOLEN.
- Remember to clear 'stolen' if add_to_page_cache() fails.

And as a cleanup on that:

- Make the bottom fall-through logic a little less convoluted. Also make
  the steal path hold an extra reference to the page, so we don't have
  to differentiate between stolen and non-stolen at the end.
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
      0568b409
  3. 30 Apr, 2006 3 commits
  5. 29 Apr, 2006 5 commits
  7. 28 Apr, 2006 27 commits