Re: pgcl-2.6.0-test5-bk3-17

[William Lee Irwin III <wli@holomorphy.com>]

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On Thu, Nov 27, 2003 at 11:21:48PM -0800, William Lee Irwin III wrote:
> Now also ported to 2.6.0-test11:
> ftp://ftp.kernel.org/pub/linux/kernel/people/wli/vm/pgcl/pgcl-2.6.0-test11-1.gz
> This also corrects some PAGE_SHIFT instances that crept into mm/mmap.c
> while I wasn't looking and drops sym2 driver changes.

Quick performance and functionality test on a 32x/64GB 700MHz P-III.
Compressed dmesg attached. Not sure where the SCSI error came from.

This seems to show that reworking the rmap interaction is a pressing
performance issue (however pressing kernel compiles can be considered
to be, never mind all the actual bugs) since the rmap functions are
burning more cpu time than bitblitting luserspace. Unfortunately there
isn't really enough disk for on-disk dbench etc. so I resorted to ramfs,
whose readdir() etc. methods appear not to be very well parallelized. I
should probably have tried ext2 on loop on ramfs or some such nonsense.

The good news is that it does still run on the thing even after all of
the massive shakeups, rewrites, and time since my last boot on it in May.


Kernel compile on ext2:

$ time make -s -j bzImage > /dev/null
arch/i386/boot/setup.S: Assembler messages:
arch/i386/boot/setup.S:168: Warning: value 0x77dfffff truncated to 0x77dfffff
Root device is (8, 2)
Boot sector 512 bytes.
Setup is 2538 bytes.
System is 1117 kB
make -s -j bzImage > /dev/null  712.96s user 284.86s system 1140% cpu 1:27.46 total

6094329 total                                      3.8079
5787061 default_idle                             90422.8281
 85912 __page_remove_rmap                       298.3056
 38331 page_remove_rmap                         140.9228
 28287 copy_folio                                88.3969
 19051 page_add_rmap                             79.3792
 14709 __copy_to_user_ll                        131.3304
  7078 __copy_user_intel                         40.2159
  6901 __copy_from_user_ll                       61.6161
  5704 __page_add_rmap                           22.2812
  4710 __d_lookup                                17.3162
  4259 zap_pte_range                              3.6464
  4127 schedule                                   2.5288
  3940 rmap_add_folio                            14.4853
  3852 kmap_atomic                                8.0250
  3258 kmem_cache_free                           33.9375
  3053 clear_page_tables                          3.3476
  2079 try_to_wake_up                             4.0605
  2012 find_get_page                             31.4375
  1815 current_kernel_time                       22.6875
  1638 kmap_atomic_sg                             4.0950
  1627 path_lookup                                4.6222


dbench on ramfs:

$ time dbench 32 
32 clients started
   0     62477  296.11 MB/sec
Throughput 296.11 MB/sec 32 procs
dbench 32  20.60s user 989.43s system 2674% cpu 37.767 total

2328901 total                                      1.4552
1335226 default_idle                             20862.9062
415966 .text.lock.libfs                         2298.1547
168210 .text.lock.dec_and_lock                  15291.8182
157310 .text.lock.dcache                        291.3148
 70329 dcache_readdir                           146.5188
 23983 atomic_dec_and_lock                      347.5797
 21502 __copy_to_user_ll                        191.9821
 18555 .text.lock.file_table                    157.2458
 16183 __copy_from_user_ll                      144.4911
 11169 d_alloc                                   23.2688
 11055 filldir64                                 40.6434
  6661 d_instantiate                             69.3854
  5826 __d_lookup                                21.4191
  5405 path_lookup                               15.3551
  4545 path_release                              71.0156
  3728 file_move                                 58.2500
  3537 d_delete                                  18.4219
  3336 fd_install                                52.1250
  3220 simple_prepare_write                      20.1250
  3081 call_rcu                                  48.1406
  2704 vfs_readdir                               21.1250


SDET 32 profile:

4605683 total                                      2.8778
3480214 default_idle                             54378.3438
212021 page_remove_rmap                         779.4890
163508 __page_remove_rmap                       567.7361
 98710 page_add_rmap                            411.2917
 87944 copy_folio                               274.8250
 31101 __page_add_rmap                          121.4883
 20883 simple_prepare_write                     130.5188
 19818 copy_page_range                           15.6788
 18555 .text.lock.dcache                         34.3611
 18277 zap_pte_range                             15.6481
 17973 rmap_add_folio                            66.0772
 17932 .text.lock.dec_and_lock                  1630.1818
 17816 __d_lookup                                65.5000
 17680 __down                                    78.9286
 16517 __copy_to_user_ll                        147.4732
 11960 atomic_dec_and_lock                      173.3333
 11795 release_pages                             36.8594
 11256 kmap_atomic                               23.4500
  9696 kmem_cache_free                          101.0000
  9622 copy_mm                                    9.5456
  9371 .text.lock.libfs                          51.7735


SDET 128 profile:

19885416 total                                     12.4250
10870694 default_idle                             169854.5938
1868923 page_remove_rmap                         6871.0404
1722495 __page_remove_rmap                       5980.8854
991381 page_add_rmap                            4130.7542
619755 __down                                   2766.7634
403192 copy_folio                               1259.9750
172220 __page_add_rmap                          672.7344
164246 rmap_add_folio                           603.8456
161239 __wake_up                                2015.4875
123047 __d_lookup                               452.3787
121684 schedule                                  74.5613
120902 zap_pte_range                            103.5120
101418 __copy_to_user_ll                        905.5179
 99572 copy_page_range                           78.7753
 95709 simple_prepare_write                     598.1812
 76676 atomic_dec_and_lock                      1111.2464
 66245 remove_shared_vm_struct                  517.5391
 64159 path_lookup                              182.2699
 61922 release_pages                            193.5062
 61415 copy_mm                                   60.9276
 61356 clear_page_tables                         67.2763


I could probably use suggestions for a more mergeable method of
mitigating the rmap functions' overheads than the currently
available mm/rmap.c rewrites.

In more relevant news, I've started taking stabs at the rvmalloc()
mess and drm, with copious help from Zwane.


-- wli

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