doc: explaining the page trick #2196
Conversation
|
Interesting! I bet we could use this trick in |
doc/basics.md
Outdated
| In effect, it means that you can almost always read a few bytes beyond your current buffer. | ||
| Thus, even though you may sometimes need to reallocate the memory to get extra padding, this should be | ||
| uncommon. However, tools such as valgrind or memory sanitizers will flag such behavior as unsafe. | ||
| While the early releases of the simdjson made use of this capability, we removed it due to avoid |
There was a problem hiding this comment.
I think we got rid of this behavior in stage 1, but we still read into the padding sometimes (in string unescaping at the least).
There was a problem hiding this comment.
I'll trim this comment since it seems unclear.
| @@ -2621,6 +2623,120 @@ Performance tips | |||
| ``` | |||
| - To better understand the operation of your On Demand parser, and whether it is performing as well as you think it should be, there is a logger feature built in to simdjson! To use it, define the pre-processor directive `SIMDJSON_VERBOSE_LOGGING` prior to including the `simdjson.h` header, which enables logging in simdjson. Run your code. It may generate a lot of logging output; adding printouts from your application that show each section may be helpful. The log's output will show step-by-step information on state, buffer pointer position, depth, and key retrieval status. Importantly, unless `SIMDJSON_VERBOSE_LOGGING` is defined, logging is entirely disabled and thus carries no overhead. | |||
There was a problem hiding this comment.
I feel like if possible we should shove this elsewhere--maybe in performance.md. It feels out of place for someone who wants to read and know all the basics. Not the biggest deal though.
There was a problem hiding this comment.
@jkeiser Right. I'll move it to performance.md. Next commit.
|
@jkeiser The last commit moves things as you suggested. I also simplified some of the discussion so that it is less confusing. |
|
Merging. There are issues with Visual Studio which are unrelated. |
Padding does not usually require allocation.