Re: [PATCH 00/12] IO-less dirty throttling v7

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On Mon, Apr 18, 2011 at 2:13 AM, Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote:
> Hi Sedat,
>
>> Please revert the last commit. It's not necessary anyway.
>>
>> commit 84a9890ddef487d9c6d70934c0a2addc65923bcf
>> Author: Wu Fengguang <fengguang.wu@xxxxxxxxx>
>> Date: Â Sat Apr 16 18:38:41 2011 -0600
>>
>> Â Â writeback: scale dirty proportions period with writeout bandwidth
>>
>> Â Â CC: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
>> Â Â Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
>
> Please do revert that commit, because I found a sleep-inside-spinlock
> bug with it. Here is the fixed one (but you don't have to track this
> optional patch).
>
> Thanks,
> Fengguang
> ---
> Subject: writeback: scale dirty proportions period with writeout bandwidth
> Date: Sat Apr 16 18:38:41 CST 2011
>
> CC: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> ---
> Âmm/page-writeback.c | Â 24 ++++++++++++------------
> Â1 file changed, 12 insertions(+), 12 deletions(-)
>
> --- linux-next.orig/mm/page-writeback.c 2011-04-17 20:52:13.000000000 +0800
> +++ linux-next/mm/page-writeback.c   Â2011-04-18 07:57:01.000000000 +0800
> @@ -121,20 +121,13 @@ static struct prop_descriptor vm_complet
> Âstatic struct prop_descriptor vm_dirties;
>
> Â/*
> - * couple the period to the dirty_ratio:
> + * couple the period to global write throughput:
> Â*
> - * Â period/2 ~ roundup_pow_of_two(dirty limit)
> + * Â period/2 ~ roundup_pow_of_two(write IO throughput)
> Â*/
> Âstatic int calc_period_shift(void)
> Â{
> - Â Â Â unsigned long dirty_total;
> -
> - Â Â Â if (vm_dirty_bytes)
> - Â Â Â Â Â Â Â dirty_total = vm_dirty_bytes / PAGE_SIZE;
> - Â Â Â else
> - Â Â Â Â Â Â Â dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) /
> - Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 100;
> - Â Â Â return 2 + ilog2(dirty_total - 1);
> + Â Â Â return 2 + ilog2(default_backing_dev_info.avg_write_bandwidth);
> Â}
>
> Â/*
> @@ -143,6 +136,13 @@ static int calc_period_shift(void)
> Âstatic void update_completion_period(void)
> Â{
> Â Â Â Âint shift = calc_period_shift();
> +
> + Â Â Â if (shift > PROP_MAX_SHIFT)
> + Â Â Â Â Â Â Â shift = PROP_MAX_SHIFT;
> +
> + Â Â Â if (abs(shift - vm_completions.pg[0].shift) <= 1)
> + Â Â Â Â Â Â Â return;
> +
> Â Â Â Âprop_change_shift(&vm_completions, shift);
> Â Â Â Âprop_change_shift(&vm_dirties, shift);
> Â}
> @@ -180,7 +180,6 @@ int dirty_ratio_handler(struct ctl_table
>
> Â Â Â Âret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> Â Â Â Âif (ret == 0 && write && vm_dirty_ratio != old_ratio) {
> - Â Â Â Â Â Â Â update_completion_period();
> Â Â Â Â Â Â Â Âvm_dirty_bytes = 0;
> Â Â Â Â}
> Â Â Â Âreturn ret;
> @@ -196,7 +195,6 @@ int dirty_bytes_handler(struct ctl_table
>
> Â Â Â Âret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
> Â Â Â Âif (ret == 0 && write && vm_dirty_bytes != old_bytes) {
> - Â Â Â Â Â Â Â update_completion_period();
> Â Â Â Â Â Â Â Âvm_dirty_ratio = 0;
> Â Â Â Â}
> Â Â Â Âreturn ret;
> @@ -1044,6 +1042,8 @@ snapshot:
> Â Â Â Âbdi->bw_time_stamp = now;
> Âunlock:
> Â Â Â Âspin_unlock(&dirty_lock);
> + Â Â Â if (gbdi->bw_time_stamp == now)
> + Â Â Â Â Â Â Â update_completion_period();
> Â}
>
> Âstatic unsigned long max_pause(struct backing_dev_info *bdi,
>

Unfortunately, this "v2" patch still breaks with gcc-4.6 here:

  LD      .tmp_vmlinux1
mm/built-in.o: In function `calc_period_shift.part.10':
page-writeback.c:(.text+0x6458): undefined reference to `____ilog2_NaN'
make[4]: *** [.tmp_vmlinux1] Error 1

My patchset against next-20110415 looks like this:

  (+) OK   writeback-dirty-throttling-v7/writeback-dirty-throttling-v7.patch
  (+) OK   writeback-dirty-throttling-post-v7/0001-writeback-i386-compile-fix.patch
  (+) OK   writeback-dirty-throttling-post-v7/0002-writeback-quick-CONFIG_BLK_DEV_THROTTLING-n-compile-.patch
  (+) OK   writeback-dirty-throttling-post-v7/0003-Revert-writeback-scale-dirty-proportions-period-with.patch
  (+) OK   writeback-dirty-throttling-v7-fix/writeback-scale-dirty-proportions-period-with-writeout-bandwidth-v2.patch

Attached are the disasm of mm/page-writeback.o (v2, gcc-4.6) and the
disasm of yesterday's experiments with gcc-4.5.

[ gcc-4.5 ]

00006574 <calc_period_shift>:
    6574:       a1 90 00 00 00          mov    0x90,%eax        6575:
R_386_32  default_backing_dev_info
    6579:       55                      push   %ebp
    657a:       89 e5                   mov    %esp,%ebp
    657c:       e8 02 f8 ff ff          call   5d83 <__ilog2_u32>
    6581:       5d                      pop    %ebp
    6582:       83 c0 02                add    $0x2,%eax
    6585:       c3                      ret

[ gcc-4.6 ]

000008c9 <calc_period_shift.part.10>:
     8c9:       8b 15 90 00 00 00       mov    0x90,%edx        8cb:
R_386_32   default_backing_dev_info
     8cf:       55                      push   %ebp
     8d0:       89 e5                   mov    %esp,%ebp
     8d2:       85 d2                   test   %edx,%edx
     8d4:       0f 88 46 01 00 00       js     a20
<calc_period_shift.part.10+0x157>
     8da:       f7 c2 00 00 00 40       test   $0x40000000,%edx
     8e0:       b8 20 00 00 00          mov    $0x20,%eax
     8e5:       0f 85 3a 01 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     8eb:       f7 c2 00 00 00 20       test   $0x20000000,%edx
     8f1:       b0 1f                   mov    $0x1f,%al
     8f3:       0f 85 2c 01 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     8f9:       f7 c2 00 00 00 10       test   $0x10000000,%edx
     8ff:       b0 1e                   mov    $0x1e,%al
     901:       0f 85 1e 01 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     907:       f7 c2 00 00 00 08       test   $0x8000000,%edx
     90d:       b0 1d                   mov    $0x1d,%al
     90f:       0f 85 10 01 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     915:       f7 c2 00 00 00 04       test   $0x4000000,%edx
     91b:       b0 1c                   mov    $0x1c,%al
     91d:       0f 85 02 01 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     923:       f7 c2 00 00 00 02       test   $0x2000000,%edx
     929:       b0 1b                   mov    $0x1b,%al
     92b:       0f 85 f4 00 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     931:       f7 c2 00 00 00 01       test   $0x1000000,%edx
     937:       b0 1a                   mov    $0x1a,%al
     939:       0f 85 e6 00 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     93f:       f7 c2 00 00 80 00       test   $0x800000,%edx
     945:       b0 19                   mov    $0x19,%al
     947:       0f 85 d8 00 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     94d:       f7 c2 00 00 40 00       test   $0x400000,%edx
     953:       b0 18                   mov    $0x18,%al
     955:       0f 85 ca 00 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     95b:       f7 c2 00 00 20 00       test   $0x200000,%edx
     961:       b0 17                   mov    $0x17,%al
     963:       0f 85 bc 00 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     969:       f7 c2 00 00 10 00       test   $0x100000,%edx
     96f:       b0 16                   mov    $0x16,%al
     971:       0f 85 ae 00 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     977:       f7 c2 00 00 08 00       test   $0x80000,%edx
     97d:       b0 15                   mov    $0x15,%al
     97f:       0f 85 a0 00 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     985:       f7 c2 00 00 04 00       test   $0x40000,%edx
     98b:       b0 14                   mov    $0x14,%al
     98d:       0f 85 92 00 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     993:       f7 c2 00 00 02 00       test   $0x20000,%edx
     999:       b0 13                   mov    $0x13,%al
     99b:       0f 85 84 00 00 00       jne    a25
<calc_period_shift.part.10+0x15c>
     9a1:       f7 c2 00 00 01 00       test   $0x10000,%edx
     9a7:       b0 12                   mov    $0x12,%al
     9a9:       75 7a                   jne    a25
<calc_period_shift.part.10+0x15c>
     9ab:       f6 c6 80                test   $0x80,%dh
     9ae:       b0 11                   mov    $0x11,%al
     9b0:       75 73                   jne    a25
<calc_period_shift.part.10+0x15c>
     9b2:       f6 c6 40                test   $0x40,%dh
     9b5:       b0 10                   mov    $0x10,%al
     9b7:       75 6c                   jne    a25
<calc_period_shift.part.10+0x15c>
     9b9:       f6 c6 20                test   $0x20,%dh
     9bc:       b0 0f                   mov    $0xf,%al
     9be:       75 65                   jne    a25
<calc_period_shift.part.10+0x15c>
     9c0:       f6 c6 10                test   $0x10,%dh
     9c3:       b0 0e                   mov    $0xe,%al
     9c5:       75 5e                   jne    a25
<calc_period_shift.part.10+0x15c>
     9c7:       f6 c6 08                test   $0x8,%dh
     9ca:       b0 0d                   mov    $0xd,%al
     9cc:       75 57                   jne    a25
<calc_period_shift.part.10+0x15c>
     9ce:       f6 c6 04                test   $0x4,%dh
     9d1:       b0 0c                   mov    $0xc,%al
     9d3:       75 50                   jne    a25
<calc_period_shift.part.10+0x15c>
     9d5:       f6 c6 02                test   $0x2,%dh
     9d8:       b0 0b                   mov    $0xb,%al
     9da:       75 49                   jne    a25
<calc_period_shift.part.10+0x15c>
     9dc:       f6 c6 01                test   $0x1,%dh
     9df:       b0 0a                   mov    $0xa,%al
     9e1:       75 42                   jne    a25
<calc_period_shift.part.10+0x15c>
     9e3:       f6 c2 80                test   $0x80,%dl
     9e6:       b0 09                   mov    $0x9,%al
     9e8:       75 3b                   jne    a25
<calc_period_shift.part.10+0x15c>
     9ea:       f6 c2 40                test   $0x40,%dl
     9ed:       b0 08                   mov    $0x8,%al
     9ef:       75 34                   jne    a25
<calc_period_shift.part.10+0x15c>
     9f1:       f6 c2 20                test   $0x20,%dl
     9f4:       b0 07                   mov    $0x7,%al
     9f6:       75 2d                   jne    a25
<calc_period_shift.part.10+0x15c>
     9f8:       f6 c2 10                test   $0x10,%dl
     9fb:       b0 06                   mov    $0x6,%al
     9fd:       75 26                   jne    a25
<calc_period_shift.part.10+0x15c>
     9ff:       f6 c2 08                test   $0x8,%dl
     a02:       b0 05                   mov    $0x5,%al
     a04:       75 1f                   jne    a25
<calc_period_shift.part.10+0x15c>
     a06:       f6 c2 04                test   $0x4,%dl
     a09:       b0 04                   mov    $0x4,%al
     a0b:       75 18                   jne    a25
<calc_period_shift.part.10+0x15c>
     a0d:       f6 c2 02                test   $0x2,%dl
     a10:       b0 03                   mov    $0x3,%al
     a12:       75 11                   jne    a25
<calc_period_shift.part.10+0x15c>
     a14:       80 e2 01                and    $0x1,%dl
     a17:       b0 02                   mov    $0x2,%al
     a19:       75 0a                   jne    a25
<calc_period_shift.part.10+0x15c>
     a1b:       e8 fc ff ff ff          call   a1c
<calc_period_shift.part.10+0x153>    a1c: R_386_PC32 ____ilog2_NaN
     a20:       b8 21 00 00 00          mov    $0x21,%eax
     a25:       5d                      pop    %ebp
     a26:       c3                      ret

00000a27 <calc_period_shift>:
     a27:       55                      push   %ebp
     a28:       83 ca ff                or     $0xffffffff,%edx
     a2b:       89 e5                   mov    %esp,%ebp
     a2d:       0f bd 05 90 00 00 00    bsr    0x90,%eax        a30:
R_386_32   default_backing_dev_info
     a34:       0f 44 c2                cmove  %edx,%eax
     a37:       5d                      pop    %ebp
     a38:       83 c0 02                add    $0x2,%eax
     a3b:       c3                      ret

- EOT -

- Sedat -

Attachment: mm_page-writeback.o_v2.disasm.xz
Description: Binary data

Attachment: gcc-4.5_mm_page-writeback.o.disasm.xz
Description: Binary data


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