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  1. 01 May, 2006 6 commits
    • Jens Axboe's avatar
      [PATCH] vmsplice: allow user to pass in gift pages · 7afa6fd0
      Jens Axboe authored 
      If SPLICE_F_GIFT is set, the user is basically giving this pages away to
the kernel. That means we can steal them for eg page cache uses instead
of copying it.

The data must be properly page aligned and also a multiple of the page size
in length.
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
      7afa6fd0
    • 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 26 commits