I applied the attached patch that Jeff supplied me and so far it is working flawlessly. I currently have less than 4% free space on my drive and the CPU usage is less then 3% with two recordings going. I'll let it run until about 2% free space just to test further.
It also _appears_ that overall CPU usage is down slightly based on the
vmstat output from when we were trying to diagnose the problem before
compared to now. The SYS CPU time was hovering between 3-10% before, and
now it seems to be between 0-2%. I haven't done any actual performance
tests though.
Jeff, what drawbacks does this patch have?
Thanks for all your hard work, I'm sure many other MythTV users will be
appreciate it.
On Thu, 2006-06-29 at 10:41 -0700, Mike Benoit wrote:
> My MythTV box recently started showing odd behavior during recordings,
> at certain times the load of the box would spike to 10+ and recordings
> would start losing frames and become unwatchable. TOP would show
> mythbackend as using 90+% SYS CPU usage, which under normal
> circumstances it normally uses about 5% USR.
>
> So I finally got around to profiling mythbackend when the load starts to
> spike. To my surprise it appears that once I have less then 10% (30GB)
> free on the drive reiserfs can't up, even just writing at 1mb/sec is too
> much for it.
>
> Is there something that can be done to fix this, 30gb seems like a lot
> of wasted space.
>
> #opreport
> CPU: CPU with timer interrupt, speed 0 MHz (estimated)
> Profiling through timer interrupt
> TIMER:0|
> samples| %|
> ------------------
> 77863 78.7856 reiserfs
> 18183 18.3984 vmlinux
> 695 0.7032 mysqld
> 452 0.4574 libc-2.4.so
> 360 0.3643 libmythtv-0.19.so.0.19.0
> 324 0.3278 ivtv
> 323 0.3268 nvidia
> 242 0.2449 libqt-mt.so.3.3.6
> 110 0.1113 libpthread-2.4.so
> 53 0.0536 libstdc++.so.6.0.8
> 35 0.0354 ld-2.4.so
> 23 0.0233 libperl.so
> 22 0.0223 libz.so.1.2.3
> <snip>
>
> #opreport -l /usr/src/linux/vmlinux
> CPU: CPU with timer interrupt, speed 0 MHz (estimated)
> Profiling through timer interrupt
> samples % symbol name
> 9607 52.8351 default_idle
> 7694 42.3142 find_next_zero_bit
> 183 1.0064 __copy_from_user_ll
> 57 0.3135 handle_IRQ_event
> 37 0.2035 __copy_to_user_ll
> 34 0.1870 ide_outb
> 30 0.1650 ide_end_request
> 22 0.1210 ioread8
> 22 0.1210 schedule
> 21 0.1155 get_page_from_freelist
> 17 0.0935 mmx_clear_page
> <snip>
>
> System Details:
> -----------------------------------------------
> Kernel v2.6.16.21 (custom compiled)
> - This issue also happened with 2.6.14 too though.
>
> Filesystem Size Used Avail Use% Mounted on
> /dev/hda1 280G 269G 12G 97% /
>
> [EMAIL PROTECTED] cat /proc/mounts
> rootfs / rootfs rw 0 0
> /dev /dev tmpfs rw 0 0
> /dev/root / reiserfs rw,noatime,nodiratime 0 0
>
> [EMAIL PROTECTED] cat /proc/cpuinfo
> processor : 0
> vendor_id : AuthenticAMD
> cpu family : 6
> model : 6
> model name : AMD Athlon(tm) XP 2100+
> stepping : 2
> cpu MHz : 1759.680
> cache size : 256 KB
>
> [EMAIL PROTECTED] free
> total used free shared buffers
> cached
> Mem: 515992 496256 19736 0 36256
> 271728
> -/+ buffers/cache: 188272 327720
> Swap: 262136 408 261728
>
> [EMAIL PROTECTED] ~]# hdparm -i /dev/hda
> /dev/hda:
> Model=ST3300622A, FwRev=3.AND, SerialNo=3NF1GAGW
> Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
> RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
> BuffType=unknown, BuffSize=16384kB, MaxMultSect=16, MultSect=16
> CurCHS=4047/16/255, CurSects=16511760, LBA=yes, LBAsects=268435455
> IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120}
> PIO modes: pio0 pio1 pio2 pio3 pio4
> DMA modes: mdma0 mdma1 mdma2
> UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
> AdvancedPM=no WriteCache=enabled
> Drive conforms to: Unspecified: ATA/ATAPI-1 ATA/ATAPI-2 ATA/ATAPI-3
> ATA/ATAPI-4 ATA/ATAPI-5 ATA/ATAPI-6 ATA/ATAPI-7
> * signifies the current active mode
>
> [EMAIL PROTECTED] ~]# hdparm -tT /dev/hda
> /dev/hda:
> Timing cached reads: 1296 MB in 2.00 seconds = 646.99 MB/sec
> Timing buffered disk reads: 166 MB in 3.02 seconds = 55.05 MB/sec
>
> vmstat 1 output:
> --------------------------------------------------------------
>
> procs -----------memory---------- ---swap-- -----io---- --system--
> ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy
> id wa
> 8 0 408 5800 29308 248604 0 0 0 1036 406 132 2 98
> 0 0
> 4 0 408 5644 29396 248608 0 0 0 1128 437 184 2 92
> 0 6
> 7 0 408 6316 29428 248020 0 0 0 1316 539 287 0 86
> 0 14
> 5 0 408 6104 29480 248180 0 0 0 588 415 187 0 99
> 0 1
> 4 0 408 5764 29536 248364 0 0 0 1092 421 172 2 97
> 1 0
> 6 0 408 6528 29592 247684 0 0 0 1092 425 161 2 98
> 0 1
> 2 1 408 6372 29676 247724 0 0 0 2304 385 170 2 97
> 1 0
> 5 0 408 6400 29676 247616 0 0 0 48 383 122 0
> 100 0 0
> 7 0 408 6192 29704 247872 0 0 0 1080 409 162 1 98
> 0 1
> 6 0 408 5720 29732 248304 0 0 0 1076 414 178 1 98
> 0 1
> 7 0 408 6348 29800 247552 0 0 0 1656 460 300 2 87
> 1 11
> 5 0 408 6628 29848 247248 0 0 0 1164 407 207 1 94
> 0 5
> 5 0 408 5884 29896 247996 0 0 4 1116 453 353 1 76
> 0 23
> 6 0 408 5640 29868 248204 0 0 0 1052 416 132 1 99
> 0 0
> 4 0 408 5772 29940 248104 0 0 0 648 490 314 1 84
> 1 14
> 6 1 408 6328 30036 247464 0 0 0 1928 488 305 2 85
> 0 13
> 4 0 408 6184 30076 247472 0 0 4 860 404 201 1 94
> 0 5
> 4 0 408 6332 30044 247328 0 0 0 1312 429 156 1 99
> 0 0
> 9 0 408 6120 30100 247580 0 0 0 604 494 305 3 81
> 1 16
> 2 1 408 6460 30140 247116 0 0 0 1372 436 315 1 79
> 0 20
> 10 0 408 6252 30176 247372 0 0 0 456 412 126 1 99
> 0 0
> 6 0 408 6432 30164 247276 0 0 4 1268 425 255 1 88
> 1 10
> 3 0 408 5688 30220 247948 0 0 0 1332 454 352 0 78
> 0 22
> 2 1 408 6352 30284 247124 0 0 0 1140 362 156 2 96
> 1 1
> 5 0 408 6564 30284 246908 0 0 0 92 472 316 2 83
> 0 15
> 5 0 408 6348 30352 247056 0 0 0 1168 506 350 0 83
> 0 17
> 4 0 408 5604 30404 247828 0 0 4 1124 448 262 2 87
> 0 11
> 3 0 408 5880 30444 247500 0 0 0 1104 426 315 2 77
> 1 20
> 2 1 408 5916 30496 247352 0 0 0 1064 365 152 1 97
> 0 2
> 7 0 408 6072 30496 247204 0 0 0 440 489 307 1 82
> 0 17
> 6 0 408 5936 30528 247288 0 0 0 816 434 130 2 98
> 0 0
> 4 0 408 5944 30588 247300 0 0 0 1108 359 172 0 98
> 0 2
> 4 0 408 5664 30624 247508 0 0 0 1444 426 161 0 99
> 1 0
> 5 0 408 6656 30608 246572 0 0 0 1220 425 163 2 98
> 0 1
> 6 0 408 6316 30656 246848 0 0 0 1552 441 180 1 98
> 0 1
> 4 0 408 6408 30632 246776 0 0 0 644 403 140 1 99
> 0 0
> 9 0 408 6072 30696 247060 0 0 4 744 496 351 2 82
> 1 16
> 5 0 408 5864 30708 247240 0 0 0 1680 509 335 1 83
> 1 15
> procs -----------memory---------- ---swap-- -----io---- --system--
> ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy
> id wa
> 3 1 408 6284 30768 246768 0 0 0 1132 434 328 1 76
> 1 22
> 6 0 408 6352 30772 246692 0 0 0 576 373 170 0 93
> 0 7
> 4 0 408 6008 30820 246932 0 0 4 612 496 322 1 83
> 0 16
> 4 0 408 6288 30836 246600 0 0 0 1484 480 304 1 85
> 0 14
> 4 0 408 6064 30896 246844 0 0 0 1136 504 337 1 84
> 1 15
> 5 0 408 5728 30900 247116 0 0 4 1188 426 156 1 99
> 0 0
> 6 0 408 5696 30968 247144 0 0 0 1104 367 123 3 97
> 0 0
> 4 0 408 5608 31016 247144 0 0 0 1152 445 378 2 74
> 1 23
> 7 0 408 5576 31008 247088 0 0 0 964 402 115 1 99
> 0 0
> 4 0 408 6328 31052 246396 0 0 0 628 355 152 1 98
> 0 1
> 5 0 408 6116 31112 246524 0 0 0 1620 472 299 2 85
> 1 12
> 2 1 408 6336 31204 246176 0 0 0 1112 367 156 2 96
> 0 2
> 7 0 408 6388 31176 246192 0 0 0 76 457 272 0 86
> 0 14
> 5 0 408 6268 31232 246284 0 0 0 1136 466 267 1 85
> 1 13
> 2 1 408 5932 31304 246616 0 0 4 2068 374 173 1 99
> 0 0
> 6 0 408 5960 31224 246564 0 0 0 104 472 273 1 84
> 0 15
> 6 0 408 5692 31308 246716 0 0 0 1160 412 206 2 94
> 0 4
> 5 0 408 5600 31336 246892 0 0 4 1660 480 289 2 86
> 0 12
> 7 0 408 6400 31336 245964 0 0 0 1052 418 160 3 97
> 0 0
> 6 0 408 6316 31292 246136 0 0 0 512 432 127 1 99
> 0 0
> 5 0 408 5856 31372 246528 0 0 0 1824 404 159 2 96
> 0 2
> 3 0 408 5880 31424 246412 0 0 0 1156 454 174 1 97
> 1 1
> 3 0 408 6024 31372 246336 0 0 0 896 399 130 0
> 100 0 0
> 5 0 408 5812 31432 246492 0 0 0 708 413 160 1 97
> 0 2
> 5 0 408 6396 31424 246024 0 0 0 1604 436 163 1 97
> 1 1
> 6 1 408 6276 31492 245924 0 0 216 1176 511 409 3 82
> 0 15
> 4 0 408 6312 31528 245944 0 0 0 1116 468 263 1 86
> 0 13
> 1 2 408 6592 31576 245628 0 0 56 1044 343 126 0 97
> 0 3
> 5 0 408 6312 31576 245904 0 0 32 48 427 155 0 97
> 0 3
> 1 0 408 5816 31624 246360 0 0 72 1796 590 834 2 40
> 35 24
> 1 1 408 16872 31704 247564 0 0 1232 248 513 1185 28 4
> 11 57
> 1 1 408 31240 31768 248520 0 0 932 92 403 996 32 4
> 10 54
> 1 0 408 29576 31880 248704 0 0 188 248 372 997 7 6
> 61 26
> 1 1 408 28284 31952 249852 0 0 316 344 402 842 20 21
> 45 13
> 0 1 408 27188 32008 250940 0 0 112 976 393 465 33 58
> 0 9
> 5 1 408 24748 32100 253228 0 0 1212 1424 571 949 31 31
> 0 37
> 2 0 408 23052 32156 255032 0 0 544 1036 415 351 16 80
> 0 4
> 0 1 408 21148 32232 256808 0 0 516 1480 454 692 33 41
> 0 25
> procs -----------memory---------- ---swap-- -----io---- --system--
> ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy
> id wa
> 2 1 408 19616 32288 258308 0 0 576 1352 414 478 33 59
> 0 8
> 4 0 408 18084 32348 259816 0 0 496 1344 423 524 29 56
> 0 15
> 5 0 408 17016 32428 260844 0 0 192 812 518 574 24 63
> 0 13
> 2 0 408 15348 32488 262444 0 0 208 1064 416 295 14 85
> 0 1
> 5 0 408 13616 32552 264104 0 0 84 1684 497 615 32 66
> 0 2
> 5 1 408 13496 32612 263992 0 0 92 1148 530 526 14 71
> 0 14
> 0 1 408 13000 32784 264556 0 0 80 1240 506 504 1 59
> 0 40
> 3 1 408 12132 32864 265324 0 0 36 612 431 438 2 65
> 0 34
> 1 1 408 10196 33048 266960 0 0 216 4 440 565 1 60
> 0 39
> 1 1 408 9252 33284 267768 0 0 168 2444 463 617 1 56
> 0 43
> 0 3 408 7208 33376 269680 0 0 32 3460 459 497 1 59
> 0 40
> 2 1 408 6416 33444 270392 0 0 24 748 448 423 0 71
> 0 29
> 0 1 408 5976 33664 270568 0 0 220 1436 481 654 2 55
> 0 43
> 1 0 408 6100 33700 270356 0 0 8 844 406 389 9 70
> 16 5
> 0 0 408 5848 33732 270568 0 0 0 1128 435 401 0 72
> 27 1
> 1 0 408 5720 33772 270664 0 0 0 852 398 350 1 73
> 25 1
> 1 0 408 6100 33780 270320 0 0 0 1216 446 522 0 54
> 45 1
> 3 0 408 5736 33780 270644 0 0 0 1092 475 736 0 32
> 67 1
> 1 0 408 6372 33952 269720 0 0 0 1040 462 522 4 69
> 26 1
> 2 0 408 6436 33944 269592 0 0 0 864 433 287 0 83
> 16 1
> 0 0 408 5848 34024 270140 0 0 4 1232 480 701 3 39
> 53 5
> 2 0 408 9196 33936 266612 0 0 104 212 596 1035 10 43
> 40 8
> 3 0 408 8824 33936 267380 0 0 0 512 388 90 0
> 100 0 0
> 4 0 408 7956 33968 268148 0 0 0 548 400 114 1 98
> 0 1
> 2 0 408 6492 34000 269604 0 0 0 892 432 629 0 38
> 61 1
> 2 0 408 6416 34084 269648 0 0 0 1712 403 591 0 40
> 58 2
> 5 0 408 6612 34120 269376 0 0 0 844 447 557 1 49
> 49 1
> 4 0 408 6424 34148 269548 0 0 0 880 465 493 0 65
> 35 0
> 1 0 408 6336 34196 269596 0 0 0 1112 475 552 3 59
> 36 2
> 4 1 408 6304 34340 269404 0 0 0 1668 378 316 0 78
> 22 0
> 3 0 408 6096 34368 269608 0 0 0 308 411 625 1 38
> 59 2
> 3 0 408 6268 34412 269372 0 0 0 1148 398 583 0 39
> 60 1
> 5 0 408 6400 34444 269264 0 0 0 824 431 414 0 67
> 33 0
>
--
Mike Benoit <[EMAIL PROTECTED]>
--- linux-2.6.17.orig/fs/reiserfs/bitmap.c 2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.17.orig.devel/fs/reiserfs/bitmap.c 2006-07-23 19:10:57.000000000 -0400
@@ -1020,7 +1020,6 @@
b_blocknr_t finish = SB_BLOCK_COUNT(s) - 1;
int passno = 0;
int nr_allocated = 0;
- int bigalloc = 0;
determine_prealloc_size(hint);
if (!hint->formatted_node) {
@@ -1047,28 +1046,9 @@
hint->preallocate = hint->prealloc_size = 0;
}
/* for unformatted nodes, force large allocations */
- bigalloc = amount_needed;
}
do {
- /* in bigalloc mode, nr_allocated should stay zero until
- * the entire allocation is filled
- */
- if (unlikely(bigalloc && nr_allocated)) {
- reiserfs_warning(s, "bigalloc is %d, nr_allocated %d\n",
- bigalloc, nr_allocated);
- /* reset things to a sane value */
- bigalloc = amount_needed - nr_allocated;
- }
- /*
- * try pass 0 and pass 1 looking for a nice big
- * contiguous allocation. Then reset and look
- * for anything you can find.
- */
- if (passno == 2 && bigalloc) {
- passno = 0;
- bigalloc = 0;
- }
switch (passno++) {
case 0: /* Search from hint->search_start to end of disk */
start = hint->search_start;
@@ -1106,8 +1086,7 @@
new_blocknrs +
nr_allocated,
start, finish,
- bigalloc ?
- bigalloc : 1,
+ 1,
amount_needed -
nr_allocated,
hint->
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