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DuaneEllis-TI
7372571276
* PR-1599 - examples/platforms/posix/flash.c fixes
* Some notes:
a) Do not change this to a for(;;) loop that writes bytes
This takes forever and causes timeouts to occur.
The math:
With pagesize = 8K pages, and n-pages=128
This turns into 1 million calls to "pwrite()"
Those 1million calls occur during startup.
the "Thread Cert" tests, in some cases start
over 30+ instances of the simulated app...
Tests actually run in parallel, in some cases there are
70 to 80 instances of the CLI app starting up. Each one
calling write - 1 million times, writing exactly 1 byte
That becomes super slow. Thus we write full pages
On a powerful platform this is fast, very fast.
On a virtual machine (ie: test-build-farm) it is slow
Result is: The Thread Cert tests fail/timeout
b) Do not allocate memory for the page via malloc/free.
Reason: this causes false failures in some test modes
Specifically when enabling the address sanitizer ...
And running thread certification tests *in*parallel*
The memory requirements become huge.
Background:
The way "asan" works is this: When you free a page
the "libasan" does not actually free the page instead
libasan poisons the page but does not actually free the
page, why? Because the goal to detect using the memory
Thus ASAN is like a giant memory leak, it must hold onto
the page so that it can detect "use-after-free"
Next (part 2)... the CERT tests, and run in parallel there
are cases where 70 to 80 instances of the CLI app run
in parallel - its a huge pseudo-memory leak times 70
Depending upon your machine you need 8 to 16gig of ram
Virtual test boxes are often configured with much less
The solution is to use a full page on the stack
it could be a static, variable however, we are
running on Linux, we have plenty of RAM..