auto tuning tcp
Andre Oppermann
oppermann at networx.ch
Tue Nov 13 12:43:44 UTC 2012
On 13.11.2012 09:41, Alfred Perlstein wrote:
> On 11/13/12 12:25 AM, Andre Oppermann wrote:
>> On 13.11.2012 09:18, Alfred Perlstein wrote:
>>> On 11/13/12 12:06 AM, Andre Oppermann wrote:
>>>> On 13.11.2012 07:45, Alfred Perlstein wrote:
>>>>> If you are concerned about the space/time tradeoff I'm pretty happy with making it 1/2, 1/4th,
>>>>> 1/8th
>>>>> the size of maxsockets. (smaller?)
>>>>>
>>>>> Would that work better?
>>>>
>>>> I'd go for 1/8 or even 1/16 with a lower bound of 512. More than
>>>> that is excessive.
>>>
>>> I'm OK with 1/8. All I'm really going for is trying to make it somewhat better than 512 when
>>> un-tuned.
>> >
>>>> PS: Please note that my patch for mbuf and maxfiles tuning is not yet
>>>> in HEAD, it's still sitting in my tcp_workqueue branch. I still have
>>>> to search for derived values that may get totally out of whack with
>>>> the new scaling scheme.
>>>>
>>> This is cool! Thank you for the feedback.
>>>
>>> Would you like me to put this on a user branch somewhere for you to merge into your perf branch?
>>
>> I can put it into my branch and also merge it to HEAD with
>> a "Submitted by: alfred" line.
>>
> Thank you, that works. Note: it's not even compile tested at this point.
>
> I should be able to do so tomorrow.
>
> Are there other hashes to look at? I noticed a few more:
>
> UDBHASHSIZE
Even busy UDP servers have only a small number of sockets open.
> netinet/tcp_hostcache.c:#define TCP_HOSTCACHE_HASHSIZE 512
This is per host, not per connection or socket. So it should by fine
and scales independently.
> netinet/sctp_constants.h:#define SCTP_TCBHASHSIZE 1024
> netinet/sctp_constants.h:#define SCTP_PCBHASHSIZE 256
Michael has look at that.
> netinet/tcp_syncache.c:#define TCP_SYNCACHE_HASHSIZE 512
Again this is not per connection or socket. It depends on the number
of concurrent SYN's waiting on SYN/ACK-ACK for a listen socket. This
should be fine and it has overflow protection. If a SYN entry is lost
it reverts to syncookies.
> Any of these look like good targets? I think most could be looked at. I've only glanced. I can
> provide deltas.
--
Andre
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