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From "Lu, Yingqi" <yingqi...@intel.com>
Subject RE: [PATCH ASF bugzilla# 55897]prefork_mpm patch with SO_REUSEPORT support
Date Sun, 01 Jun 2014 06:47:49 GMT
Hi Jim,

Regarding to your comment #2, yes, you are right, it should be ap_mpm_pod_killpg(pod, retained->max_daemons_limit,
i). Thanks very much for catching this.

Regarding to your comment #1, the patch modifies the dummy_connection(ap_pod_t *pod) to be
dummy_connection(ap_pod_t *pod, int child_bucket). Inside the function, the reference listen
statement is mpm_listen[child_bucket]. And, ap_mpm_pod_signal() calls dummy_connection().


Can we just modify the return of ap_mpm_pod_signal() from dummy_connection(pod) to dummy_connection(pod,
0) and add ap_mpm_pod_signal_ex()? 

Or, if we need to keep ap_mpm_pod_signal() exactly as the original, I can modify dummy_connection()
to send dummy data via all the duplicated listen statements. Then, we do not need child_bucket
as the input parameter for dummy_connection(). In this case, we do not need adding ap_mpm_pod_signal_ex()
too.

I already tested the code for the above approaches and they both work. 

Please let me know which way you think is better. I can quickly send you an update for review.

Thanks,
Yingqi

-----Original Message-----
From: Lu, Yingqi 
Sent: Saturday, May 31, 2014 3:28 PM
To: <dev@httpd.apache.org>
Subject: Re: [PATCH ASF bugzilla# 55897]prefork_mpm patch with SO_REUSEPORT support

Hi Jim,

Thanks very much for your email! I will look into both of them and send an update tonight!

Thanks,
Yingqi

> On May 31, 2014, at 9:43 AM, "Jim Jagielski" <jim@jaguNET.com> wrote:
> 
> I also see:
> 
>         /* kill off the idle ones */
> -        ap_mpm_pod_killpg(pod, retained->max_daemons_limit);
> +        for (i = 0; i < num_buckets; i++) {
> +            ap_mpm_pod_killpg(pod[i], i, retained->max_daemons_limit);
> +        }
> 
> 
> Is that right? Why isn't it: ap_mpm_pod_killpg(pod, retained->max_daemons_limit, i);
??
> 
> /**
>  * Write data to the pipe-of-death, signalling that all child process
>  * should die.
>  * @param pod The pipe-of-death to write to.
>  * @param num The number of child processes to kill
> + * @param my_bucket the bucket that holds the dying child process.
>  */
> -AP_DECLARE(void) ap_mpm_pod_killpg(ap_pod_t *pod, int num);
> +AP_DECLARE(void) ap_mpm_pod_killpg(ap_pod_t *pod, int num, int 
> +child_bucket);
> 
> Isn't 'num' the same in both implementation??
> 
>> On May 31, 2014, at 12:03 PM, Jim Jagielski <jim@jagunet.com> wrote:
>> 
>> Sorry I didn't catch this earlier:
>> 
>> I see
>> 
>> +++ httpd-trunk.new/include/mpm_common.h    2014-05-16 13:07:03.892987491 -0400
>> @@ -267,16 +267,18 @@
>> * Write data to the pipe-of-death, signalling that one child process
>> * should die.
>> * @param pod the pipe-of-death to write to.
>> + * @param my_bucket the bucket that holds the dying child process.
>> */
>> -AP_DECLARE(apr_status_t) ap_mpm_pod_signal(ap_pod_t *pod);
>> +AP_DECLARE(apr_status_t) ap_mpm_pod_signal(ap_pod_t *pod, int 
>> +child_bucket);
>> 
>> We can change the API at this point. We could add another function, 
>> eg ap_mpm_pod_signal_ex() which takes the int param, but we can't 
>> modify ap_mpm_pod_signal() itself.
>> 
>>> On May 30, 2014, at 11:15 AM, Lu, Yingqi <yingqi.lu@intel.com> wrote:
>>> 
>>> Thank you very much!
>>> 
>>> Thanks,
>>> Yingqi
>>> 
>>> -----Original Message-----
>>> From: Jim Jagielski [mailto:jim@jaguNET.com]
>>> Sent: Friday, May 30, 2014 7:07 AM
>>> To: dev@httpd.apache.org
>>> Subject: Re: [PATCH ASF bugzilla# 55897]prefork_mpm patch with 
>>> SO_REUSEPORT support
>>> 
>>> Thx! Let me review. My plan is to fold into trunk this weekend.
>>> 
>>>> On May 16, 2014, at 2:53 PM, Lu, Yingqi <yingqi.lu@intel.com> wrote:
>>>> 
>>>> Hi Jim,
>>>> 
>>>> Thanks very much for clarifying this with me. I added #ifdef in the code
to check _SC_NPROCESSORS_ONLN in the so_reuseport patch. Bucket patch does not use this parameter
so that it remains the same.
>>>> 
>>>> Attached are the two most recent patches. I already updated the bugzilla
#55897 as well.
>>>> 
>>>> Thanks,
>>>> Yingqi
>>>> 
>>>> -----Original Message-----
>>>> From: Jim Jagielski [mailto:jim@jaguNET.com]
>>>> Sent: Thursday, May 15, 2014 7:53 AM
>>>> To: dev@httpd.apache.org
>>>> Subject: Re: [PATCH ASF bugzilla# 55897]prefork_mpm patch with 
>>>> SO_REUSEPORT support
>>>> 
>>>> I was thinking more about the sysconf(_SC_NPROCESSORS_ONLN) stuff...
>>>> We could either check for that during config/build or protect it with a #ifdef
in the code (and create some logging so the admin nows if it was found or not).
>>>> 
>>>>> On May 14, 2014, at 11:59 AM, Lu, Yingqi <yingqi.lu@intel.com>
wrote:
>>>>> 
>>>>> Hi Jim,
>>>>> 
>>>>> Thanks very much for your email.
>>>>> 
>>>>> In the SO_REUSEPORT patch, SO_REUSEPORT support is checked inside listen.c
file. If the feature is not supported on the OS (for example, Linux kernel < 3.9), it will
fall back to the original behavior. 
>>>>> 
>>>>> In the bucket patch, there is no need to check the params. With single
listen statement, it is just the default behavior. 
>>>>> 
>>>>> Please let me know if this answers your question.
>>>>> 
>>>>> Thanks,
>>>>> Yingqi
>>>>> 
>>>>> -----Original Message-----
>>>>> From: Jim Jagielski [mailto:jim@jaguNET.com]
>>>>> Sent: Wednesday, May 14, 2014 6:57 AM
>>>>> To: dev@httpd.apache.org
>>>>> Subject: Re: [PATCH ASF bugzilla# 55897]prefork_mpm patch with 
>>>>> SO_REUSEPORT support
>>>>> 
>>>>> This is very cool!
>>>>> 
>>>>> mod_status assumes that sysconf() exists, but do we need to do a config
check on the params we use in these patches?
>>>>> We look OK on Linux, FreeBSD and OSX...
>>>>> 
>>>>> I'm +1 on folding into trunk.
>>>>> 
>>>>>> On May 13, 2014, at 7:55 PM, Lu, Yingqi <yingqi.lu@intel.com>
wrote:
>>>>>> 
>>>>>> Dear All,
>>>>>> 
>>>>>> During the last couple weeks, I spent some time extending the original
two patches from prefork MPM only to all three Linux MPMs (prefork, worker and event). Attached
is the latest version of the two patches. Bugzilla database has also been updated already.
The ID for the two patches are #55897 and #56279. Please refer to messages below for details
on both of the patches.
>>>>>> 
>>>>>> Quick test result on modern dual socket Intel platform (Linux 
>>>>>> Kernel
>>>>>> 3.13.9) SO_REUSEPORT patch (bugzilla #55897)
>>>>>> 1.       Prefork MPM: 1 listen statement: 2.16X throughput improvement;
2 listen statements: 2.33X throughput improvement
>>>>>> 2.       Worker MPM: 1 listen statement: 10% throughput improvement;
2 listen statements: 35% throughput improvement
>>>>>> 3.       Event MPM: 1 listen statement: 13% throughput improvement;
2 listen statements: throughput parity, but 62% response time reduction (with patch, 38% response
time as original SW)
>>>>>> 
>>>>>> Bucket patch (bugzilla #56279, only impact multiple listen statement
case)
>>>>>> 1.       Prefork MPM: 2 listen statements: 42% throughput improvement
>>>>>> 2.       Worker MPM: 2 listen statements: 7% throughput improvement
>>>>>> 
>>>>>> In all the above testing cases, significant response time reductions
are observed, even with throughput improvements.
>>>>>> 
>>>>>> Please let me know your feedback and comments.
>>>>>> 
>>>>>> Thanks,
>>>>>> Yingqi
>>>>>> Software and workloads used in performance tests may have been optimized
for performance only on Intel microprocessors. Performance tests, such as SYSmark and MobileMark,
are measured using specific computer systems, components, software, operations and functions.
Any change to any of those factors may cause the results to vary. You should consult other
information and performance tests to assist you in fully evaluating your contemplated purchases,
including the performance of that product when combined with other products.
>>>>>> 
>>>>>> From: Lu, Yingqi [mailto:yingqi.lu@intel.com]
>>>>>> Sent: Monday, March 17, 2014 1:41 PM
>>>>>> To: dev@httpd.apache.org
>>>>>> Subject: RE: FW: [PATCH ASF bugzilla# 55897]prefork_mpm patch 
>>>>>> with SO_REUSEPORT support
>>>>>> 
>>>>>> Dear all,
>>>>>> 
>>>>>> Based on the feedback we received, we modified this patch. Here is
the most recent version. We also modified the Bugzilla database(Bugzilla# 55897 for SO_REUSEPORT
patch; Bugzilla# 56279 for bucket patch).
>>>>>> 
>>>>>> Below are the changes we made into this new version:
>>>>>> 
>>>>>> According to Yann Ylavic and other people's comments, we separate
the original patch between with and without SO_REUSEPORT into two separated patches. The SO_REUSEPORT
patch does not change the original listen sockets, it just duplicate the original one into
multiple ones. Since the listen sockets are identical, there is no need to change the idle_server_maintenance
function. The bucket patch (without SO_REUSEPORT), on the other hand, it breaks down the original
listen record (if there are multiple listen socks) to multiple listen record linked lists.
In this case, idle_server_maintenance is implemented at bucket level to address the situation
that imbalanced traffic occurs among different listen sockets/children buckets. In the bucket
patch, the polling in the child process is removed since each child only listens to 1 sock.
>>>>>> 
>>>>>> According to Arkadiusz Miskiewicz's comment, we make the "detection
of SO_REUSEPORT" at run time.
>>>>>> 
>>>>>> According to Jeff Trawick's comments, 1. We generate the patches

>>>>>> against the httpd trunk.
>>>>>> 2. We tested the current patches and they do not impact event and
worker mpms. If current patches can be accepted, we would be happy to extend them to other
Linux based mpms. There are not much code changes, but require some time to setup the workload
to test.
>>>>>> 3. We removed unnecessary comments and changed APLOGNO(). We also
changed some of the parameter/variable/function names to better represent their meanings.
>>>>>> 4. There should be no build-in limitations for SO_REUSEPORT patch.
For bucket patch, the only thing is the number of children bucket only scales to MAX_SPAWN_RATE.
If there are more than 32 (current default MAX_SPQN_RATE) listen statements specified in the
httpd.conf, the number of buckets will be fixed to 32. The reason for this is because that
we implement the idle_server_maintenance at bucket level, each bucket's own max_spawn_rate
is set to MAX_SPAWN_RATE/num_buckets.
>>>>>> 
>>>>>> Again, thanks very much for all the comments and feedback. Please
let us know if there are more changes we need to complete to make them accepted.
>>>>>> 
>>>>>> Thanks,
>>>>>> Yingqi Lu
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> From: Lu, Yingqi
>>>>>> Sent: Tuesday, March 04, 2014 10:43 AM
>>>>>> To: dev@httpd.apache.org
>>>>>> Subject: RE: FW: [PATCH ASF bugzilla# 55897]prefork_mpm patch 
>>>>>> with SO_REUSEPORT support
>>>>>> 
>>>>>> Hi Jeff,
>>>>>> 
>>>>>> Thanks very much for your time reviewing the patch! We will modify
the patch according to your comments and repost it here.
>>>>>> 
>>>>>> Thanks,
>>>>>> Yingqi
>>>>>> 
>>>>>> From: Jeff Trawick [mailto:trawick@gmail.com]
>>>>>> Sent: Tuesday, March 04, 2014 10:08 AM
>>>>>> To: Apache HTTP Server Development List
>>>>>> Subject: Re: FW: [PATCH ASF bugzilla# 55897]prefork_mpm patch 
>>>>>> with SO_REUSEPORT support
>>>>>> 
>>>>>> On Tue, Mar 4, 2014 at 10:35 AM, Lu, Yingqi <yingqi.lu@intel.com>
wrote:
>>>>>> Hi All,
>>>>>> 
>>>>>> I just want to ping again on this patch to gather your feedback and
comments. Please refer to the messages below for patch details.
>>>>>> 
>>>>>> If you need any additional information/supporting data, please let
us know as well.
>>>>>> 
>>>>>> Yeah, it has been on my todo list, but I don't have time to give

>>>>>> an in depth review at the moment.  Here are a few questions/comments.
>>>>>> (And you'll have to deal with the fact that it is unnecessarily 
>>>>>> tedious for me to evaluate higher-level considerations if there 
>>>>>> are a lot of distractions, such as the code comments below ;)  
>>>>>> But others are of course free to chime in.)
>>>>>> 
>>>>>> The patch should be against httpd trunk.  It probably won't take
much time for you to create that patch and confirm basic operation.
>>>>>> 
>>>>>> What is the impact to other MPMs, even if they shouldn't use or don't
have the necessary code to use SO_REUSEPORT at this time?
>>>>>> 
>>>>>> Have you tried the event MPM?
>>>>>> 
>>>>>> Is there a way for the admin to choose this behavior?  Most won't
care, but everyone's behavior is changed AFAICT.
>>>>>> 
>>>>>> Are there built-in limitations in this patch that we should be aware
of?  E.g., the free slot/spawn rate changes suggest to me that there can't be more than 1025
children???
>>>>>> 
>>>>>> We should assume for now that there's no reason this couldn't be
committed to trunk after review/rework, so make sure it is as close as you can get it to what
you think is the final form.
>>>>>> 
>>>>>> For the configure-time check for 3.9 kernel: I think we'd also 
>>>>>> use AC_TRY_COMPILE at configure time to confirm that the 
>>>>>> SO_REUSEPORT definition is available, and not enable it if the 
>>>>>> system includes doesn't define it.  (Does that cause a problem 
>>>>>> for any significant number of people?)
>>>>>> 
>>>>>> Don't mention the patch in the patch ;) (e.g., "This function is

>>>>>> added for the patch.")
>>>>>> 
>>>>>> Incomplete comments on style/syntax issues:
>>>>>> 
>>>>>> * mixing declarations and statements (e.g., "duplr->next = 0;

>>>>>> apr_socket_t *temps;") isn't supported by all compilers and is 
>>>>>> distracting when reviewing
>>>>>> * suitable identifier names (e.g., fix global variable "flag" and

>>>>>> whatever else isn't appropriate; "ap_post_config_listeners" 
>>>>>> should be renamed to indicate what it does
>>>>>> * APLOGNO(99999) and comments about fixing it: Instead put "APLOGNO()"

>>>>>> and don't add reminders in comments
>>>>>> * this doesn't seem portable: "int free_slots[MAX_SPAWN_RATE/num_buckets];"
>>>>>> and so on
>>>>>> 
>>>>>> 
>>>>>> Thanks,
>>>>>> Yingqi
>>>>>> 
>>>>>> 
>>>>>> From: Lu, Yingqi
>>>>>> Sent: Friday, January 24, 2014 3:26 PM
>>>>>> To: dev@httpd.apache.org
>>>>>> Subject: [PATCH ASF bugzilla# 55897]prefork_mpm patch with 
>>>>>> SO_REUSEPORT support
>>>>>> 
>>>>>> Dear All,
>>>>>> 
>>>>>> Our analysis of Apache httpd 2.4.7 prefork mpm, on 32 and 64 thread
Intel Xeon 2600 series systems, using an open source three tier social networking web server
workload, revealed performance scaling issues.  In current software single listen statement
(listen 80) provides better scalability due to un-serialized accept. However, when system
is under very high load, this can lead to big number of child processes stuck in D state.
On the other hand, the serialized accept approach cannot scale with the high load either.
 In our analysis, a 32-thread system, with 2 listen statements specified, could scale to just
70% utilization, and a 64-thread system, with signal listen statement specified (listen 80,
4 network interfaces), could scale to only 60% utilization.
>>>>>> 
>>>>>> Based on those findings, we created a prototype patch for prefork
mpm which extends performance and thread utilization. In Linux kernel newer than 3.9, SO_REUSEPORT
is enabled. This feature allows multiple sockets listen to the same IP:port and automatically
round robins connections. We use this feature to create multiple duplicated listener records
of the original one and partition the child processes into buckets. Each bucket listens to
1 IP:port. In case of old kernel which does not have the SO_REUSEPORT enabled, we modified
the "multiple listen statement case" by creating 1 listen record for each listen statement
and partitioning the child processes into different buckets. Each bucket listens to 1 IP:port.
>>>>>> 
>>>>>> Quick tests of the patch, running the same workload, demonstrated
a 22% throughput increase with 32-threads system and 2 listen statements (Linux kernel 3.10.4).
With the older kernel (Linux Kernel 3.8.8, without SO_REUSEPORT), 10% performance gain was
measured. With single listen statement (listen 80) configuration, we observed over 2X performance
improvements on modern dual socket Intel platforms (Linux Kernel 3.10.4). We also observed
big reduction in response time, in addition to the throughput improvement gained in our tests
1.
>>>>>> 
>>>>>> Following the feedback from the bugzilla website where we originally
submitted the patch, we removed the dependency of APR change to simplify the patch testing
process. Thanks Jeff Trawick for his good suggestion! We are also actively working on extending
the patch to worker and event MPMs, as a next step. Meanwhile, we would like to gather comments
from all of you on the current prefork patch. Please take some time test it and let us know
how it works in your environment.
>>>>>> 
>>>>>> This is our first patch to the Apache community. Please help us review
it and let us know if there is anything we might revise to improve it. Your feedback is very
much appreciated.
>>>>>> 
>>>>>> Configuration:
>>>>>> <IfModule prefork.c>
>>>>>> ListenBacklog 105384
>>>>>> ServerLimit 105000
>>>>>> MaxClients 1024
>>>>>> MaxRequestsPerChild 0
>>>>>> StartServers 64
>>>>>> MinSpareServers 8
>>>>>> MaxSpareServers 16
>>>>>> </IfModule>
>>>>>> 
>>>>>> 1. Software and workloads used in performance tests may have been
optimized for performance only on Intel microprocessors. Performance tests, such as SYSmark
and MobileMark, are measured using specific computer systems, components, software, operations
and functions. Any change to any of those factors may cause the results to vary. You should
consult other information and performance tests to assist you in fully evaluating your contemplated
purchases, including the performance of that product when combined with other products.
>>>>>> 
>>>>>> Thanks,
>>>>>> Yingqi
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> --
>>>>>> Born in Roswell... married an alien...
>>>>>> http://emptyhammock.com/
>>>>>> http://edjective.org/
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> --
>>>>>> Born in Roswell... married an alien...
>>>>>> http://emptyhammock.com/
>>>>>> http://edjective.org/
>>>>>> 
>>>>>> <httpd_trunk_so_reuseport.patch><httpd_trunk_bucket.patch>
>>>> 
>>>> <httpd_trunk_so_reuseport.patch><httpd_trunk_bucket.patch>
> 

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