On Mon, Jun 19, 2017 at 05:03:16PM +0100, Al Viro wrote:
On Mon, Jun 19, 2017 at 09:01:36PM +0800, Sean Fu wrote:
quoted
Make alloc_page_buffers support circular buffer list and initialise
b_state field.
Optimize the performance by removing the buffer list traversal to create
circular buffer list.
quoted
- bh = head = alloc_page_buffers(page, blocksize, 1);
+ bh = head = alloc_page_buffers(page, blocksize, 1, 0, 0);
Frankly, I don't like that change of calling conventions; it's very easy to
mess the order of arguments when using interfaces like that and it's hell
to find when trying to debug the resulting mess.
Do you really get an observable change in performance? What loads are
triggering it?
Sorry for my mistake.
Infact, The time of writting a large file depends on saveral other
factors, eg system workload.
Yesterday, I tried to test the time of single calling create_empty_buffers by kretprobe
and found that the performance difference is too small to measure it.
before:
[ 944.632027] create_empty_buffers returned 878736736 and took 2160 ns
to execute
[ 944.632286] create_empty_buffers returned 878962832 and took 451 ns
to execute
[ 944.632302] create_empty_buffers returned 878962016 and took 226 ns
to execute
[ 944.632728] create_empty_buffers returned 878962832 and took 235 ns
to execute
[ 944.633105] create_empty_buffers returned 878962832 and took 167 ns
to execute
[ 944.633421] create_empty_buffers returned 878962832 and took 160 ns
to execute
after:
[39209.076519] create_empty_buffers returned 383804768 and took 1666 ns
to execute
[39209.077032] create_empty_buffers returned 383804768 and took 366 ns
to execute
[39209.077120] create_empty_buffers returned 558412336 and took 179 ns
to execute
[39209.077127] create_empty_buffers returned 558413152 and took 148 ns
to execute
[39209.077525] create_empty_buffers returned 558412336 and took 201 ns
to execute
[39209.078255] create_empty_buffers returned 814328768 and took 880 ns
to execute
[39209.078498] create_empty_buffers returned 558412336 and took 564 ns
to execute
[39209.078737] create_empty_buffers returned 558413152 and took 196 ns
to execute
This patch also complicates code.
Please ignore it.
Thanks all of you.