I played with oprofile for a while, and it seems that in case of null
encryption, scatterwalk related code takes most of the cpu cycles.
Tunnel mode ESP with null-encryption/sha1 (throughput 51MBits/sec),
following are the top contenders:
samples % symbol name
5794 18.9192 crypt
4812 15.7127 scatterwalk_done
3354 10.9518 sha1_transform
2530 8.2612 page_address
2469 8.0620 scatterwalk_copychunks
2458 8.0261 scatterwalk_map
1440 4.7020 kmap_atomic
1360 4.4408 default_idle
1077 3.5167 scatterwalk_whichbuf
930 3.0367 kunmap_atomic
731 2.3869 handle_IRQ_event
676 2.2073 ecb_process
381 1.2441 ide_intr
Tunnel mode ESP with aes/sha1 (throughput 114MBits/sec), following are
the top contenders:
samples % symbol name
9056 29.6122 default_idle
7245 23.6904 sha1_transform
3933 12.8605 aes_enc_blk
931 3.0443 cbc_process
792 2.5898 crypt
716 2.3412 scatterwalk_done
519 1.6971 handle_IRQ_event
433 1.4159 sha1_update
412 1.3472 pskb_expand_head
380 1.2426 csum_partial
373 1.2197 page_address
368 1.2033 scatterwalk_map
345 1.1281 scatterwalk_copychunks
Is there any place where I can find documentation about what exactly
scatterwalk does?
Thanks,
Shekhar
> -----Original Message-----
> From: netdev-bounce@xxxxxxxxxxx [mailto:netdev-bounce@xxxxxxxxxxx] On
> Behalf Of bert hubert
> Sent: Wednesday, December 29, 2004 4:12 AM
> To: Shekhar Kshirsagar
> Cc: Networking Team
> Subject: Re: 2.6 IPSec Throughput puzzle
>
> On Tue, Dec 28, 2004 at 07:17:26PM -0800, Shekhar Kshirsagar wrote:
>
> > I'm really puzzled with the performance results I'm getting. The
> > performance drop with AH seems high, but worst is performance drop
with
> > null-esp in transport mode. Another strange observation is that DES
> > throughput is greater than null encryption throughput.
>
> Thanks for doing these benchmarks! I did some myself some time ago,
but my
> hardware isn't representative of anything (consisting of a pentium pro
200
> against a P3 1GHz).
>
> > Throughput without IPSec : 936 MBits/s ( 25% CPU Util)
> > Transport mode AH - SHA1 : 398 MBits/s (100% CPU Util)
> > Transport mode ESP - null/SHA1: 62 MBits/s (100% CPU Util)
> > Transport mode ESP - des/SHA1 : 111 MBits/s (100% CPU Util)
> > Transport mode ESP - 3des/SHA1: 54 MBits/s (100% CPU Util)
> > Transport mode ESP - aes/SHA1 : 192 MBits/s (100% CPU Util)
> >
> > Do these numbers sound reasonable?
> > (I don't have any iptable rules)
>
> It is very easy to use oprofile these days, I suggest you profile for
a
> bit,
> should easily tell you what the culprit is. 62MBit/s sounds very low.
>
> Good luck!
>
> --
> http://www.PowerDNS.com Open source, database driven DNS Software
> http://lartc.org Linux Advanced Routing & Traffic Control
HOWTO
>
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