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From Jim Jagielski <...@jaguNET.com>
Subject Re: [PATCH ASF bugzilla# 55897]prefork_mpm patch with SO_REUSEPORT support
Date Wed, 14 May 2014 13:56:55 GMT
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>


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