heads-up: preempt kernel and tux NO-GO

heads-up: preempt kernel and tux NO-GO

[J Sloan]

Hi -

I have been looking into the tux2 webserver -
Man, what a thing of beauty. A web benchmark
that sends the load on the web server to 150
when running apache results in a load average
of  maybe 2 when running tux, and much faster
results to boot - anyway, I digress....

I built 2.4.16+low-latency+preempt+tux2, and
started testing it. To my horror, the webserver
died - I checked the logs and found an oops -
(for your edification, I attach it below)

So, I figured, preempt and low latency don't
mix well - I'll just build a kernel with tux and
preempt.

To my horror, the new kernel without the
low latency patch oopsed immediately as
well, as soon as I started an apachebench
run from a remote testing box.

(for you edification, I include this oops also)

I removed the preempt patch and basically
compiled just 2.4.16+tux, and hammered on
it for several hours - rock solid.

So, there is an issue with tux and the preempt
patch - I've got big plans for tux atm, so for
now I will have to do without preempt -

Thanks & Regards,

jjs

Re: heads-up: preempt kernel and tux NO-GO

[Oliver Xymoron]

On Tue, 27 Nov 2001, J Sloan wrote:

> I have been looking into the tux2 webserver -
> Man, what a thing of beauty. A web benchmark
> that sends the load on the web server to 150
> when running apache results in a load average
> of  maybe 2 when running tux, and much faster
> results to boot - anyway, I digress....

Loadavg isn't much of a measure here, it's a measure of the length of the
runnable queue. If you've only got two processes because your server has a
thread per processor, then yes, you'll see lower loadavg, but not lower
load. A real measure would look at idle percentage and throughput.

--
 "Love the dolphins," she advised him. "Write by W.A.S.T.E.."

Re: heads-up: preempt kernel and tux NO-GO

[J Sloan]

Oliver Xymoron wrote:

> On Tue, 27 Nov 2001, J Sloan wrote:
>
> > I have been looking into the tux2 webserver -
> > Man, what a thing of beauty. A web benchmark
> > that sends the load on the web server to 150
> > when running apache results in a load average
> > of  maybe 2 when running tux, and much faster
> > results to boot - anyway, I digress....
>
> Loadavg isn't much of a measure here, it's a measure of the length of the
> runnable queue. If you've only got two processes because your server has a
> thread per processor, then yes, you'll see lower loadavg, but not lower
> load. A real measure would look at idle percentage and throughput.

That's easily done, and we know that load average
is a measure of tasks waiting to run - but rather
than throw more statistics around, I can say that
a Linux desktop running tux remains responsive
under a http load that would tend to monopolize it's
attention under apache -

Now I'm not knocking apache of course, it's the
standard these days, and there's nothing more
flexible or reliable - but there is indeed a niche
for a small, blindingly fast server like tux - and I
intend to explore that niche in coming months.

cu

jjs

Re: heads-up: preempt kernel and tux NO-GO

[Andrew Morton]

Oliver Xymoron wrote:
> 
> On Tue, 27 Nov 2001, J Sloan wrote:
> 
> > I have been looking into the tux2 webserver -
> > Man, what a thing of beauty. A web benchmark
> > that sends the load on the web server to 150
> > when running apache results in a load average
> > of  maybe 2 when running tux, and much faster
> > results to boot - anyway, I digress....
> 
> Loadavg isn't much of a measure here, it's a measure of the length of the
> runnable queue. If you've only got two processes because your server has a
> thread per processor, then yes, you'll see lower loadavg, but not lower
> load. A real measure would look at idle percentage and throughput.

Even idle percentage is quite misleading.  Lots of interrupt
processing gets credited to the idle task and you don't see
it at all with normal accounting tools.

The `subtractive' approach is more accurate.  See how much
processing capacity is left behind when all the foreground
task and interrupt processing is complete.

Grab http://www.zip.com.au/~akpm/linux/zc.tar.gz
Type make
run ./cyclesoak -C
run ./cyclesoak

easy.

Re: heads-up: preempt kernel and tux NO-GO

[Robert Love]

On Tue, 2001-11-27 at 20:17, J Sloan wrote:

> So, there is an issue with tux and the preempt
> patch - I've got big plans for tux atm, so for
> now I will have to do without preempt -

Tux makes heavy use of per-CPU data and some of it is undoubtedly not
preempt-safe.  It is probably trivial to fix but would take some
familiarity with the codebase...Ingo would know best.  Its not on the
top of my todo list, but I will look into it. 

	Robert Love

interrupt ?

[McEnroe]

hi,

what is fast and slow interrupt ?
what is the difference between this ?
bye



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data point: tux and low-latency patches OK

[J Sloan]

Just to follow up, I compiled 2.4.16 with the
low latency patch from Andrew Morton, as
well as the 2.4.16-disk-i/o-responsiveness
patch from Andrew, and tux-full-2.4.16-A3.

I hammered tux all night with an apachebench
script, and it never hiccupped. So, while tux
and preempt don't play well together, tux and
low-latency seem to get along just fine.

Regards,

jjs


J Sloan wrote:

> I built 2.4.16+low-latency+preempt+tux2, and
> started testing it. To my horror, the webserver
> died - I checked the logs and found an oops -
> (for your edification, I attach it below)
>
> So, I figured, preempt and low latency don't
> mix well - I'll just build a kernel with tux and
> preempt.
>
> To my horror, the new kernel without the
> low latency patch oopsed immediately as
> well, as soon as I started an apachebench
> run from a remote testing box.
>
> (for you edification, I include this oops also)
>
> I removed the preempt patch and basically
> compiled just 2.4.16+tux, and hammered on
> it for several hours - rock solid.
>
> So, there is an issue with tux and the preempt
> patch - I've got big plans for tux atm, so for
> now I will have to do without preempt -
>
> Thanks & Regards,
>
> jjs
>
> -
> 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/

Re: interrupt ?

[Robert Love]

On Wed, 2001-11-28 at 20:18, McEnroe wrote:

> what is fast and slow interrupt ?
> what is the difference between this ?

fast interrupts occur with interrupts disabled, and are expected to be
completed quickly -- they are performed by the interrupt handlers
themselves.

a slow interrupt occurs with interrupts enabled, such as bottom half
tasks.

	Robert Love

Re: interrupt ?

[Mike Fedyk]

On Thu, Nov 29, 2001 at 12:07:37PM -0500, Robert Love wrote:
> On Wed, 2001-11-28 at 20:18, McEnroe wrote:
> 
> > what is fast and slow interrupt ?
> > what is the difference between this ?
> 
> fast interrupts occur with interrupts disabled, and are expected to be
> completed quickly -- they are performed by the interrupt handlers
> themselves.
> 
> a slow interrupt occurs with interrupts enabled, such as bottom half
> tasks.
> 

IIRC, bottom half is mostly used by network packet processing.

heads-up: preempt kernel and tux NO-GO

[J Sloan]

[-- Attachment #1: Type: text/plain, Size: 50 bytes --]

Forgot to attach the oopses -

Here they are:





[-- Attachment #2: 2.4.16-tux+preempt+lowlat.ksymoops.out --]
[-- Type: text/plain, Size: 5367 bytes --]

ksymoops 2.4.0 on i686 2.4.16.  Options used
     -V (default)
     -k /proc/ksyms (default)
     -l /proc/modules (default)
     -o /lib/modules/2.4.16/ (default)
     -m /boot/System.map (specified)

Warning (compare_maps): mismatch on symbol ftp_bandwidth  , tux says d28fd1b0, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28fa350.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol ftp_bytes_sent  , tux says d28fd1ac, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28fa34c.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol last_measurement  , tux says d28fd1a8, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28fa348.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol nr_tux_threads  , tux says d28fd220, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28fa3c0.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol threadinfo  , tux says d28fd240, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28fa3e0.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol nlmsvc_ops  , lockd says d28c1010, /lib/modules/2.4.16/kernel/fs/lockd/lockd.o says d28c0468.  Ignoring /lib/modules/2.4.16/kernel/fs/lockd/lockd.o entry
Warning (compare_maps): mismatch on symbol nfs_debug  , sunrpc says d28b3264, /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o says d28b2f44.  Ignoring /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o entry
Warning (compare_maps): mismatch on symbol nfsd_debug  , sunrpc says d28b3268, /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o says d28b2f48.  Ignoring /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o entry
Warning (compare_maps): mismatch on symbol nlm_debug  , sunrpc says d28b326c, /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o says d28b2f4c.  Ignoring /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o entry
Warning (compare_maps): mismatch on symbol rpc_debug  , sunrpc says d28b3260, /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o says d28b2f40.  Ignoring /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o entry
Warning (compare_maps): mismatch on symbol raid1_retry_tail  , raid1 says d2894b38, /lib/modules/2.4.16/kernel/drivers/md/raid1.o says d28949e0.  Ignoring /lib/modules/2.4.16/kernel/drivers/md/raid1.o entry
Warning (compare_maps): mismatch on symbol md_size  , md says d288cc80, /lib/modules/2.4.16/kernel/drivers/md/md.o says d288caa0.  Ignoring /lib/modules/2.4.16/kernel/drivers/md/md.o entry
Warning (compare_maps): mismatch on symbol mddev_map  , md says d288c480, /lib/modules/2.4.16/kernel/drivers/md/md.o says d288c2a0.  Ignoring /lib/modules/2.4.16/kernel/drivers/md/md.o entry
Unable to handle kernel NULL pointer dereference at virtual address 00000008
c0127cbf
*pde = 00000000
Oops: 0000
CPU:    0
EIP:    0010:[<c0127cbf>]    Not tainted
Using defaults from ksymoops -t elf32-i386 -a i386
EFLAGS: 00010296
eax: 00000000   ebx: 00000000   ecx: 00000000   edx: cdbce05c
esi: cdbce000   edi: 00000001   ebp: cfb3deb0   esp: cfb3de78
ds: 0018   es: 0018   ss: 0018
Process tux (pid: 4569, stackpage=cfb3d000)
Stack: cfb3c000 00000000 cf12aea0 d0162380 c01127bc cfb3c000 cfb3dee4 c01071a1 
       cdbce000 00000000 00000001 00000000 cdbce000 00000001 cfb3dee4 d28e1d42 
       cdbce05c cdbce07c cdbce0c8 d28e1910 00000001 cfb3ded0 d0162380 cdbce000 
Call Trace: [<c01127bc>] [<c01071a1>] [<d28e1d42>] [<d28e1910>] [<d28e6b11>] 
   [<d28dfaf0>] [<d28e0f38>] [<d28fd240>] [<d28ec025>] [<d28fd240>] [<d28fd240>] 
   [<d28ee19e>] [<d28fd240>] [<c0134f08>] [<d28fd240>] [<d28fd240>] [<c01bbba5>] 
   [<c01070cb>] 
Code: 8b 40 08 8b b8 ac 00 00 00 8b 47 20 89 45 e0 0f b7 50 30 66 

>>EIP; c0127cbf <do_generic_file_read+f/510>   <=====
Trace; c01127bc <preempt_schedule+2c/40>
Trace; c01071a1 <ret_from_exception+42/49>
Trace; d28e1d42 <[tux]generic_send_file+e2/1d0>
Trace; d28e1910 <[tux]sock_send_actor+0/240>
Trace; d28e6b11 <[tux]http_send_body+71/110>
Trace; d28dfaf0 <[tux]tux_schedule_atom+50/60>
Trace; d28e0f38 <[tux]process_requests+118/160>
Trace; d28fd240 <[tux]__module_kernel_version+0/16>
Trace; d28ec025 <[tux]event_loop+65/1b0>
Trace; d28fd240 <[tux]__module_kernel_version+0/16>
Trace; d28fd240 <[tux]__module_kernel_version+0/16>
Trace; d28ee19e <[tux]__sys_tux+5ee/ba0>
Trace; d28fd240 <[tux]__module_kernel_version+0/16>
Trace; c0134f08 <sys_chdir+128/140>
Trace; d28fd240 <[tux]__module_kernel_version+0/16>
Trace; d28fd240 <[tux]__module_kernel_version+0/16>
Trace; c01bbba5 <sys_tux+25/100>
Trace; c01070cb <system_call+33/38>
Code;  c0127cbf <do_generic_file_read+f/510>
00000000 <_EIP>:
Code;  c0127cbf <do_generic_file_read+f/510>   <=====
   0:   8b 40 08                  mov    0x8(%eax),%eax   <=====
Code;  c0127cc2 <do_generic_file_read+12/510>
   3:   8b b8 ac 00 00 00         mov    0xac(%eax),%edi
Code;  c0127cc8 <do_generic_file_read+18/510>
   9:   8b 47 20                  mov    0x20(%edi),%eax
Code;  c0127ccb <do_generic_file_read+1b/510>
   c:   89 45 e0                  mov    %eax,0xffffffe0(%ebp)
Code;  c0127cce <do_generic_file_read+1e/510>
   f:   0f b7 50 30               movzwl 0x30(%eax),%edx
Code;  c0127cd2 <do_generic_file_read+22/510>
  13:   66                        data16


13 warnings issued.  Results may not be reliable.

[-- Attachment #3: 2.4.16-tux+preempt.ksymoops.out --]
[-- Type: text/plain, Size: 7642 bytes --]

ksymoops 2.4.0 on i686 2.4.16.  Options used
     -V (default)
     -k /proc/ksyms (default)
     -l /proc/modules (default)
     -o /lib/modules/2.4.16/ (default)
     -m /boot/System.map (specified)

Warning (compare_maps): mismatch on symbol ftp_bandwidth  , tux says d28c11b0, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28be350.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol ftp_bytes_sent  , tux says d28c11ac, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28be34c.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol last_measurement  , tux says d28c11a8, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28be348.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol nr_tux_threads  , tux says d28c1220, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28be3c0.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol threadinfo  , tux says d28c1240, /lib/modules/2.4.16/kernel/net/tux/tux.o says d28be3e0.  Ignoring /lib/modules/2.4.16/kernel/net/tux/tux.o entry
Warning (compare_maps): mismatch on symbol nlmsvc_ops  , lockd says d30e5010, /lib/modules/2.4.16/kernel/fs/lockd/lockd.o says d30e4468.  Ignoring /lib/modules/2.4.16/kernel/fs/lockd/lockd.o entry
Warning (compare_maps): mismatch on symbol nfs_debug  , sunrpc says d30d7264, /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o says d30d6f44.  Ignoring /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o entry
Warning (compare_maps): mismatch on symbol nfsd_debug  , sunrpc says d30d7268, /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o says d30d6f48.  Ignoring /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o entry
Warning (compare_maps): mismatch on symbol nlm_debug  , sunrpc says d30d726c, /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o says d30d6f4c.  Ignoring /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o entry
Warning (compare_maps): mismatch on symbol rpc_debug  , sunrpc says d30d7260, /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o says d30d6f40.  Ignoring /lib/modules/2.4.16/kernel/net/sunrpc/sunrpc.o entry
Warning (compare_maps): mismatch on symbol raid1_retry_tail  , raid1 says d2894b38, /lib/modules/2.4.16/kernel/drivers/md/raid1.o says d28949e0.  Ignoring /lib/modules/2.4.16/kernel/drivers/md/raid1.o entry
Warning (compare_maps): mismatch on symbol md_size  , md says d288cc80, /lib/modules/2.4.16/kernel/drivers/md/md.o says d288caa0.  Ignoring /lib/modules/2.4.16/kernel/drivers/md/md.o entry
Warning (compare_maps): mismatch on symbol mddev_map  , md says d288c480, /lib/modules/2.4.16/kernel/drivers/md/md.o says d288c2a0.  Ignoring /lib/modules/2.4.16/kernel/drivers/md/md.o entry
Unable to handle kernel NULL pointer dereference at virtual address 00000008
c01279bf
*pde = 00000000
Oops: 0000
CPU:    0
EIP:    0010:[<c01279bf>]    Not tainted
Using defaults from ksymoops -t elf32-i386 -a i386
EFLAGS: 00010296
eax: 00000000   ebx: 00000000   ecx: 00000000   edx: cf3d285c
esi: cf3d2800   edi: 00000001   ebp: d0195eb0   esp: d0195e78
ds: 0018   es: 0018   ss: 0018
Process tux (pid: 659, stackpage=d0195000)
Stack: 00001000 00000000 ced32440 ce03a560 00000551 00000018 cf3d6440 00000012 
       cf3d2800 00000000 00000001 00000000 cf3d2800 00000001 d0195ee4 d28a5d42 
       cf3d285c cf3d287c cf3d28c8 d28a5910 00000001 d0195ed0 ce03a560 cf3d2800 
Call Trace: [<d28a5d42>] [<d28a5910>] [<d28aab11>] [<d28a3af0>] [<d28a4f38>] 
   [<d28c1240>] [<d28b0025>] [<d28c1240>] [<d28c1240>] [<d28b219e>] [<d28c1240>] 
   [<c0134a58>] [<d28c1240>] [<d28c1240>] [<c01bb265>] [<c01070cb>] 
Code: 8b 40 08 8b b8 ac 00 00 00 8b 47 20 89 45 e0 0f b7 50 30 66 

>>EIP; c01279bf <do_generic_file_read+f/4e0>   <=====
Trace; d28a5d42 <[tux]generic_send_file+e2/1d0>
Trace; d28a5910 <[tux]sock_send_actor+0/240>
Trace; d28aab11 <[tux]http_send_body+71/110>
Trace; d28a3af0 <[tux]tux_schedule_atom+50/60>
Trace; d28a4f38 <[tux]process_requests+118/160>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; d28b0025 <[tux]event_loop+65/1b0>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; d28b219e <[tux]__sys_tux+5ee/ba0>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; c0134a58 <sys_chdir+128/140>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; c01bb265 <sys_tux+25/100>
Trace; c01070cb <system_call+33/38>
Code;  c01279bf <do_generic_file_read+f/4e0>
00000000 <_EIP>:
Code;  c01279bf <do_generic_file_read+f/4e0>   <=====
   0:   8b 40 08                  mov    0x8(%eax),%eax   <=====
Code;  c01279c2 <do_generic_file_read+12/4e0>
   3:   8b b8 ac 00 00 00         mov    0xac(%eax),%edi
Code;  c01279c8 <do_generic_file_read+18/4e0>
   9:   8b 47 20                  mov    0x20(%edi),%eax
Code;  c01279cb <do_generic_file_read+1b/4e0>
   c:   89 45 e0                  mov    %eax,0xffffffe0(%ebp)
Code;  c01279ce <do_generic_file_read+1e/4e0>
   f:   0f b7 50 30               movzwl 0x30(%eax),%edx
Code;  c01279d2 <do_generic_file_read+22/4e0>
  13:   66                        data16

Unable to handle kernel NULL pointer dereference at virtual address 00000008
c01279bf
*pde = 00000000
Oops: 0000
CPU:    0
EIP:    0010:[<c01279bf>]    Not tainted
EFLAGS: 00010296
eax: 00000000   ebx: 00000000   ecx: 00000000   edx: cde4d85c
esi: cde4d800   edi: 00000001   ebp: d0247eb0   esp: d0247e78
ds: 0018   es: 0018   ss: 0018
Process tux (pid: 2610, stackpage=d0247000)
Stack: 00001000 00000000 cf9c8f00 cee5cb60 000007c1 00000009 cf3d6440 00000000 
       cde4d800 00000000 00000001 00000000 cde4d800 00000001 d0247ee4 d28a5d42 
       cde4d85c cde4d87c cde4d8c8 d28a5910 00000001 d0247ed0 cee5cb60 cde4d800 
Call Trace: [<d28a5d42>] [<d28a5910>] [<d28aab11>] [<d28a3af0>] [<d28a4f38>] 
   [<d28c1240>] [<d28b0025>] [<d28c1240>] [<d28c1240>] [<d28b219e>] [<d28c1240>] 
   [<c0134a58>] [<d28c1240>] [<d28c1240>] [<c01bb265>] [<c01070cb>] 
Code: 8b 40 08 8b b8 ac 00 00 00 8b 47 20 89 45 e0 0f b7 50 30 66 

>>EIP; c01279bf <do_generic_file_read+f/4e0>   <=====
Trace; d28a5d42 <[tux]generic_send_file+e2/1d0>
Trace; d28a5910 <[tux]sock_send_actor+0/240>
Trace; d28aab11 <[tux]http_send_body+71/110>
Trace; d28a3af0 <[tux]tux_schedule_atom+50/60>
Trace; d28a4f38 <[tux]process_requests+118/160>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; d28b0025 <[tux]event_loop+65/1b0>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; d28b219e <[tux]__sys_tux+5ee/ba0>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; c0134a58 <sys_chdir+128/140>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; d28c1240 <[tux]__module_kernel_version+0/16>
Trace; c01bb265 <sys_tux+25/100>
Trace; c01070cb <system_call+33/38>
Code;  c01279bf <do_generic_file_read+f/4e0>
00000000 <_EIP>:
Code;  c01279bf <do_generic_file_read+f/4e0>   <=====
   0:   8b 40 08                  mov    0x8(%eax),%eax   <=====
Code;  c01279c2 <do_generic_file_read+12/4e0>
   3:   8b b8 ac 00 00 00         mov    0xac(%eax),%edi
Code;  c01279c8 <do_generic_file_read+18/4e0>
   9:   8b 47 20                  mov    0x20(%edi),%eax
Code;  c01279cb <do_generic_file_read+1b/4e0>
   c:   89 45 e0                  mov    %eax,0xffffffe0(%ebp)
Code;  c01279ce <do_generic_file_read+1e/4e0>
   f:   0f b7 50 30               movzwl 0x30(%eax),%edx
Code;  c01279d2 <do_generic_file_read+22/4e0>
  13:   66                        data16


13 warnings issued.  Results may not be reliable.