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Subject2.5.66-mm3 - bad ext2 performance ?
Date
Hi,

This is kind of extreem. But I have 1070 LUNS and I mkfs/mounted (ext2) all
these and running "fsx" on all of them.

I see very bad IO rate on the machine. fsx with O_DIRECT seems to be
doing okay. Any ideas on why regular filesystem (buffered) IO sucks ?
I dont' see even cache increasing ..

Thanks,
Badari

vmstat:
======
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
1089 0 3 0 2597396 169324 219896 0 0 0 2304 1221 330 68 32 0
1093 0 4 0 2596732 169400 219820 0 0 0 1969 1195 332 68 32 0
1090 0 5 0 2599076 169452 217688 0 0 0 2611 1234 523 67 33 0
1089 0 5 0 2595908 169500 220500 0 0 0 2034 1195 345 68 32 0
1085 0 4 0 2595292 169584 221716 0 0 0 2444 1244 305 68 32 0
1082 0 5 0 2598204 169620 219080 0 0 0 2790 1234 442 67 33 0
1081 0 5 0 2595252 169680 222140 0 0 0 1980 1208 278 68 32 0
1077 0 4 0 2595084 169708 222372 0 0 0 2481 1257 377 67 33 0
1075 0 5 0 2598980 169736 218704 0 0 0 2057 1187 448 67 33 0


10 second profile output:
====================
c0137860 __filemap_fdatawrite 331 1.8807
c0137810 remove_from_page_cache 333 4.1625
c0187480 proc_pid_stat 334 0.2747
c0157130 __clear_page_buffers 347 4.3375
c01589a0 set_bh_page 350 5.4688
c0158110 create_buffers 352 2.0000
c013d3a0 do_page_cache_readahead 365 0.8449
c01a3e50 grab_block 366 0.7148
c0157cc0 mark_buffer_dirty_inode 379 3.9479
c0171db0 dnotify_parent 394 1.5391
c01588e0 __bread 407 6.3594
c02947c0 scsi_request_fn 407 0.5653
c01710f0 inode_setattr 413 0.8327
c015a970 drop_buffers 415 2.1615
c0208800 __lookup 429 1.5772
c015aa30 try_to_free_buffers 464 1.7059
c013ace0 bad_range 495 5.1562
c0138100 find_get_pages 514 4.5893
c015abd0 recalc_bh_state 530 3.6806
c013cc60 test_clear_page_dirty 532 6.6500
c0159580 block_read_full_page 541 0.7194
c01a6bd0 ext2_alloc_branch 544 1.0303
c017af50 aio_complete 554 0.9112
c015aca0 free_buffer_head 556 6.9500
c015ac60 alloc_buffer_head 568 8.8750
c01588a0 __getblk 599 9.3594
c01a74d0 ext2_free_branches 600 1.6304
c01a3850 ext2_get_group_desc 615 4.2708
c013dc20 check_poison_obj 632 1.5800
c0158b50 create_empty_buffers 634 2.6417
c0170e90 inode_change_ok 637 1.0477
c013b520 __alloc_pages 654 0.8516
c01385f0 file_read_actor 655 3.1490
c015acf0 init_buffer_head 661 13.7708
c01416e0 truncate_complete_page 683 5.3359
c01557a0 generic_file_llseek 709 3.4087
c0137f70 find_lock_page 719 3.2098
c011d4e0 __might_sleep 737 7.6771
c01a3bd0 ext2_free_blocks 818 1.2781
c0158c40 unmap_underlying_metadata 876 9.1250
c01584e0 mark_buffer_dirty 880 13.7500
c013b090 prep_new_page 925 14.4531
c0156c50 fget 1001 10.4271
c01594d0 __block_commit_write 1014 5.7614
c01092d0 system_call 1102 25.0455
c02087b0 radix_tree_lookup 1151 14.3875
c0138240 do_generic_mapping_read 1188 1.2585
c0156fd0 unlock_buffer 1208 18.8750
c01a6810 ext2_alloc_block 1232 6.4167
c0158520 __brelse 1233 25.6875
c0137ac0 add_to_page_cache 1236 4.8281
c0141810 truncate_inode_pages 1304 1.6633
c013cb40 __set_page_dirty_nobuffers 1338 6.4327
c01a68d0 ext2_block_to_path 1383 4.1161
c01a4050 ext2_new_block 1474 1.2122
c0176a00 __mark_inode_dirty 1577 4.9281
c0139470 generic_file_aio_write_nolock 1939 0.7869
c01412f0 __pagevec_lru_add 2157 5.8614
c0141020 release_pages 2203 4.1723
c0137d00 unlock_page 2283 28.5375
c0123d60 current_kernel_time 2446 30.5750
c0137ec0 find_get_page 2604 32.5500
c01590b0 __block_prepare_write 2654 2.5133
c013b2b0 free_hot_cold_page 2687 10.4961
c0119740 kmap_atomic 2813 19.5347
c0140e00 mark_page_accessed 2905 36.3125
c01587a0 __find_get_block 3392 13.2500
c01a6a20 ext2_get_branch 3497 11.5033
c013b3d0 buffered_rmqueue 3517 10.4673
c0157500 __find_get_block_slow 3564 8.5673
c0158a40 block_invalidatepage 3620 13.3088
c01a6de0 ext2_get_block 5432 5.3889
c01197d0 kunmap_atomic 6303 56.2768
c013dbe0 fprob 10266 160.4062
c013f920 kmem_cache_free 16922 29.3785
c020a3d0 __copy_from_user_ll 18886 168.6250
c013f570 kmem_cache_alloc 19822 58.9940
c020a360 __copy_to_user_ll 31509 281.3304
c0177b40 do_mpage_readpage 48937 45.6502

vmstat output for O_DIRECT (fsx):
===========================
procs memory swap io system cpu
r b w swpd free buff cache si so bi bo in cs us sy id
36 1034 5 0 2756980 150676 83844 0 0 43269 57496 9446 8861 70 30 0
45 1025 0 0 2757172 150728 83532 0 0 39107 53281 8499 8053 70 30 0
21 1049 3 0 2757252 150744 83516 0 0 40467 53607 8665 8128 70 30 0
57 1013 3 0 2757380 150756 83504 0 0 41798 54403 8842 8291 70 30 0
97 974 3 0 2757316 150780 83480 0 0 45418 59685 9657 8639 70 30 0
241 830 5 0 2756932 150852 83148 0 0 60914 81615 13457 11604 70 30 0
194 878 5 0 2757044 150920 83600 0 0 74382 90858 15219 12747 70 30 0

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