Hi,
The most interesting part first.
With or without Andrew Mortons lowlatency patch
this exact sample shows up often(in 10 - 25 ms hits):
[shrink_mmap+66/504]
Since my latency profiling patch samples IP at jiffies
I would have expected more diverted locations but for
some reason it almost always samples at that point...
Is this due to cache misses?
[Included disassembly of shrink_mmap for reference]
========================
Kernel 2.4.0-test5-pre4:
shrink_mmap is hit nine times all at [shrink_mmap+66/504]
When rewriting a file i hit a latency of > 60 ms
(can slab poisoning be a cause?)
[try_to_free_buffers][block_flushpage][__remove_from_lru_list]
[truncate_inode_pages][__free_pages_ok]
and on another occasion
[unmap_buffer][kmem_cache_free][__free_pages_ok]
At first streaming copy a 36 ms hit.
[block_flushpage][truncate_inode_pages]
When running a dbench 16
shrink_mmap reports again at same location
and finally a try_to_free_buffers
Running mmap002 gives LOTS of reports with a maximum of 151 ms
[set_bh_page+1/64] [block_getblk+34/824] [wake_up_process+6/216]
[block_getblk+150/824] [do_buffer_fdatasync+26/124]
[do_buffer_fdatasync+26/124] [writeout_one_page+27/80]
[writeout_one_page+27/80] [do_buffer_fdatasync+26/124]
[generic_make_request+1706/1744][writeout_one_page+11/80]
[ll_rw_block+223/376] [generic_make_request+1706/1744]
[ll_rw_block+104/376] [generic_make_request+1706/1744]
I included the addresses in this. You see that some gets sampled
at same location all the time; generic_make_request is one
but ll_rw_block gets different locations. But I got very
few samples of these => no statistical relevance.
===================
With Andrew Mortons lowlatency patch things look better.
[reapplied from test3, not the latest...]
Only hurt by occasional shrink_mmap:
[shrink_mmap+66/504] nine times and
two times at [shrink_mmap+85/504]
and swapper doing something for 31 ms that did not get
sampled???
Trying a dbench16 again [shrink_mmap+66/504] and at different
occasions (< 11 ms):
[ide_dmaproc]
[try_to_free_buffers]
[__remove_from_lru_list]
Running the "Don't do that" mmap002 the maximum latency
is 23 ms !
-- Home page: http://www.norran.net/nra02596/
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This archive was generated by hypermail 2b29 : Wed Jul 26 2000 - 06:16:24 EDT