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Scaling doc update

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Olof hagsand 2019-04-17 17:53:40 +02:00
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doc/scaling/large-lists.md
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@ -139,7 +139,7 @@ This section shows the results of the measurements as defined in [Tests](#tests)
### Profiling ### Profiling
An example profiling of the most demanding case was made: Put single restconf for with 5000 existing entries. An example profiling of the most demanding case was made: Put single restconf for with 5000 existing entries.
The tool used is valgrind/callgrind with the following approximate result: The tool used is valgrind/callgrind with the following approximate result (percentage of total cycles):
* from_rpc_callback 100% * from_rpc_callback 100%
* from_client_commit 65% * from_client_commit 65%
* candidate_commit 65% * candidate_commit 65%
@ -155,7 +155,14 @@ The tool used is valgrind/callgrind with the following approximate result:
* xml_chardata_encode 12% * xml_chardata_encode 12%
It can be seen that most cycles are spend in file copying and writing It can be seen that most cycles are spend in file copying and writing
to file which explains the linear behaviour. the existing datastore to file. This explains the linear behaviour, ie
the larger existing datastore, the larger number of cycles spent.
Why is the existing datastore accessed in this way? When a small PUT request is received, several things happen:
* The existing candidate database is modified with the change and written to disk. (35%)
* The difference between candidate and running is computed (13%)
* The new candidate is validated (10%)
* The candidate db is copied to running (29%)
## 5. Discussion ## 5. Discussion
@ -186,19 +193,18 @@ performance CPUs, such as 100K entries on a x86_64 in the results, but
it also means that very large lists may not be supported, and that the it also means that very large lists may not be supported, and that the
system degrades with the size of the lists. system degrades with the size of the lists.
Examining the profiling of the most demanding Restconf PUT case Examining the profiling of the most demanding Restconf PUT case, most
cycles are spent on handling writing and copying the existing datastore.
Concluding, the Concluding, the
## 6. Future work ## 6. Future work
It is recommended that the following items should be studied: * Improve access of single list elements to sub-linear performance.
* Try to improve the access of single list elements, to sub-linear perforamnce.
* CLI access on large lists (not included in this study) * CLI access on large lists (not included in this study)
## 7. References ## 7. References
[RFC6241](https://tools.ietf.org/html/rfc6241) "Network Configuration Protocol (NETCONF)" * [RFC6241](https://tools.ietf.org/html/rfc6241) "Network Configuration Protocol (NETCONF)"
[RFC8040](https://tools.ietf.org/html/rfc8040) "RESTCONF Protocol" * [RFC8040](https://tools.ietf.org/html/rfc8040) "RESTCONF Protocol"
[i686](https://ark.intel.com/content/www/us/en/ark/products/27235/intel-core-duo-processor-t2400-2m-cache-1-83-ghz-667-mhz-fsb.html) * [plot_perf.sh](../../test/plot_perf.sh) Test script
[plot_perf.sh](../test/plot_perf.sh) Test script