Re: Squid 3.2 performance question

On 27/03/2012 4:22 a.m., Alexander Komyagin wrote:
> On Fri, 2012-03-23 at 19:46 +0100, Henrik Nordström wrote:
>> fre 2012-03-23 klockan 19:49 +0400 skrev Alexander Komyagin:
>>
>>> It seems I finally figured out where the problem is. Squid 3.2.0.16
>>> performs host verification for each request. And this verification
>>> produces the call to libc getaddrinfo() function (converting IP address
>>> from text to numeric in my case), but uClibc implementation of this
>>> functions looks like not aware of AF_HOSTNUMERIC hint flag, thus
>>> performing full lookup (I haven't checked details yet). With RSBAC-Net
>>> turned on it's too much overhead. (Actually there are two calls for such
>>> conversion per request - one more is in url.cc:urlParseFinish()
>>> function)
>> Why is the overhead with RSBAC-Net that high in this case?
>>
>> getaddrinfo() is a quite frequenty used call.
>>
>> But I agree that getaddrinfo for converting textual ip to addrinfo to
>> compare with resolved hostname may be a bit overkill. Not even sure why
>> we are converting textual IP to to addrinfo there, we should already
>> have it in IpAddress internal representaion form.
>>
>>> After adding a special hack for numeric IP address conversion requests
>>> in Squid (avoiding call to real getaddrinfo() in that case), the
>>> performance problem has gone (workers work fine too!).
>> Good!
>>
>>
>>
> And here is the mentioned patch. I guarded it with "#ifdef __UCLIBC__",
> so it can be seamlessly integrated into upstream if needed. But still it
> would be better to wait until uClibc is fixed.
>
> Also falling back to bundled functions as Amos suggests, in case uClibc
> is used, can't be done without some additional modifications to them
> (for example, their declarations conflict with ones in netdb.h file,
> which can't be dropped).
>

Thank you for the patch.

Unfortunately we are trying to get all hacks like this out of the main
squid code and into compat/*. So ...

compat/getaddrinfo.* are part of the Squid sources, we are free to edit
if necessary. Please adjust them in-place to add what alterations are
needed by uClibC, inside the appropriate #if wrappings of course, and
add a change entry at the top.
  That removes the need for a special new hack file and __* definitions.

We will also have to figure out some way to make ./configure detect
uclibc and link the getaddr* files to compat as needed. In absence of
that, #include "compat/getaddrinfo.c" can be done in compat/compat.cc
within special case #if wrappings.

Amos
Received on Wed Mar 28 2012 - 09:30:18 MDT