Re: Serious Kernel slowdown with HIMEM (4Gig) in 2.6.7

From: Lawrence E. Freil
Date: Sat Aug 14 2004 - 11:46:49 EST


On Sat Aug 14th, Martin J. Bligh wrote:
>Does time indicate more systime or user time? If it's systime (probably is)
>please take a kernel profile of each (see Documentation/basic_profiling.txt).
>That'll give us a much better clue what's going on.
>
>M.

Martin, the time is almost exclusively listed as "user" in the the "time"
results:

FAST (with mem=800M): time ls -laR /home/groups/sysmbase >/dev/null

real 0m0.122s
user 0m0.101s
sys 0m0.021s

SLOW (without mem=800M): time ls -laR /home/groups/sysmbase >/dev/null
real 0m5.175s
user 0m5.145s
sys 0m0.030s

Though there is a consistant sys component that is slightly higher. I ran
profiles three times for "fast" and three times for "slow". Here they are

FAST profile 1:
33 __do_softirq 0.2578
1 groups_search 0.0094
1 in_group_p 0.0085
1 do_mmap_pgoff 0.0006
5 __d_lookup 0.0208
1 xfs_dir2_leaf_getdents 0.0003
1 xfs_trans_brelse 0.0035
6 strncpy_from_user 0.0606
49 total 0.0000

FAST profile 2:
3 system_call 0.0682
1 do_page_fault 0.0008
1 groups_search 0.0094
1 sys_lstat64 0.0175
1 follow_mount 0.0073
1 do_lookup 0.0062
3 link_path_walk 0.0015
5 __d_lookup 0.0208
2 write_profile 0.0312
1 xfs_dir2_put_dirent64_direct 0.0067
1 xfs_dir2_put_dirent64_uio 0.0049
1 xfs_dir2_leaf_getdents 0.0003
4 strncpy_from_user 0.0404
1 __copy_user_intel 0.0058
1 __copy_to_user_ll 0.0093
27 total 0.0000

FAST profile 3:
2 system_call 0.0455
1 groups_search 0.0094
1 in_group_p 0.0085
1 buffered_rmqueue 0.0028
1 find_vma_prev 0.0123
1 cp_new_stat64 0.0037
2 follow_mount 0.0146
4 link_path_walk 0.0020
2 dput 0.0058
4 __d_lookup 0.0167
1 de_put 0.0097
3 write_profile 0.0469
2 strncpy_from_user 0.0202
1 __copy_user_intel 0.0058
26 total 0.0000

And here are the three "SLOW" profiles:

SLOW profile 1:
4 system_call 0.0909
2 groups_search 0.0189
1 free_hot_cold_page 0.0043
1 kmem_cache_alloc 0.0089
1 kmem_cache_free 0.0132
1 __pagevec_lru_add_active 0.0060
1 do_wp_page 0.0013
1 do_anonymous_page 0.0027
3 do_no_page 0.0040
1 vfs_getattr 0.0065
2 follow_mount 0.0146
2 do_lookup 0.0124
5 link_path_walk 0.0024
1 path_lookup 0.0030
1 dput 0.0029
6 __d_lookup 0.0250
3 write_profile 0.0469
1 xfs_bmapi 0.0002
1 xfs_dir2_block_getdents 0.0012
2 strncpy_from_user 0.0202
2 __copy_user_intel 0.0116
7 __copy_to_user_ll 0.0648
49 total 0.0000

SLOW profile 2:
2 system_call 0.0455
2 do_page_fault 0.0015
1 zap_pte_range 0.0017
1 do_anonymous_page 0.0027
2 do_no_page 0.0027
1 follow_mount 0.0073
1 do_lookup 0.0062
4 link_path_walk 0.0020
1 filldir64 0.0043
10 __d_lookup 0.0417
3 write_profile 0.0469
1 linvfs_getattr 0.0159
4 strncpy_from_user 0.0404
1 __copy_user_intel 0.0058
3 __copy_to_user_ll 0.0278
1 ata_interrupt 0.0037
38 total 0.0000

SLOW profile 3:
4 system_call 0.0909
1 __might_sleep 0.0063
1 in_group_p 0.0085
1 wake_up_page 0.0175
1 prep_new_page 0.0123
1 kmem_cache_free 0.0132
2 do_no_page 0.0027
1 sys_llseek 0.0051
1 vfs_getattr 0.0065
1 getname 0.0041
3 link_path_walk 0.0015
1 path_lookup 0.0030
10 __d_lookup 0.0417
2 write_profile 0.0312
1 xfs_da_brelse 0.0034
1 xfs_dir2_put_dirent64_direct 0.0067
4 strncpy_from_user 0.0404
4 __copy_user_intel 0.0233
2 __copy_to_user_ll 0.0185
42 total 0.0000

Hope this helps.



--
Lawrence Freil Email:lef@xxxxxxxxx
1768 Old Country Place Phone:(770) 667-9274
Woodstock, GA 30188


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/