Re: Intel P6 vs P7 system call performance

Andrew Morton (akpm@digeo.com)
Tue, 17 Dec 2002 20:53:38 -0800


Stephen Rothwell wrote:
>
> Hi Linus, Andrew,
>
> On Tue, 17 Dec 2002 20:07:53 -0800 (PST) Linus Torvalds <torvalds@transmeta.com> wrote:
> >
> > Btw, on another tangent - Andrew Morton reports that APM is unhappy about
> > the fact that the fast system call stuff required us to move the segments
> > around a bit. That's probably because the APM code has the old APM segment
> > numbers hardcoded somewhere, but I don't see where (I certainly knew about
> > the segment number issue, and tried to update the cases I saw).
>
> I looked at this yesterday and decided that it was OK as well.
>
> > Debugging help would be appreciated, especially from somebody who knows
> > the APM code.
>
> It would help to know what "unhappy" means :-)

The lcall seems to be going awry. It oopses when apmd starts up,
and the sysenter patch is the trigger.

CPU: 0
EIP: 00b8:[<000044d7>] Not tainted
EFLAGS: 00010202
EIP is at 0x44d7
eax: 000000c8 ebx: 00000001 ecx: 00000000 edx: 00000000
esi: c02e0091 edi: 000000ff ebp: ceed1ec4 esp: ceed1e74
ds: 0000 es: 0000 ss: 0068
Process apmd (pid: 679, threadinfo=ceed0000 task=cfa058a0)
Stack: 0000530a 00b844e8 00000000 ceed1ec4 c0112739 00000060 ceed1ec4 000000ff
00000068 00000068 ceed1f32 c02e0091 000000ff 00000202 ceed0000 cf706c24
00000000 00000000 c0130000 c1740000 ceed1f04 c0112b72 0000530a 00000001
Call Trace:
[<c0112739>] apm_bios_call+0x75/0xf4
[<c0130000>] cache_init_objs+0x34/0xd8
[<c0112b72>] apm_get_power_status+0x42/0x84
[<c012d843>] __alloc_pages+0x77/0x244
[<c0113828>] apm_get_info+0x38/0xe4
[<c016982d>] proc_file_read+0xa9/0x1ac
[<c0141b53>] vfs_read+0xb7/0x138
[<c0141dee>] sys_read+0x2a/0x40
[<c0108e67>] syscall_call+0x7/0xb

> Does the following fix it for you? Untested, assumes cache lines are 32
> bytes.
>

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