mrs: make quarantine overhead tunable #2376
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If defined at compile time, QUARANTINE_HIGHWATER limited the size of the quarantine to QUARANTINE_HIGHWATER bytes. Given the vast range of working set sizes this isn't particularly useful except perhaps to set it to 0. The environment variable _RUNTIME_REVOCATION_EVERY_FREE_ENABLE and associated sysctl now serves this purpose.
Use of this macro was removed with store-side revocation support. Fixes: 62e9115 mrs: remove store-side support")
This allow more granularity including allowing quarantine to exceed 1/2
the size of the heap.
Replace QUARANTINE_RATIO with QUARANTINE_NUMERATOR and
QUARANTINE_DENOMINATOR. The quarantine is flushed when:
QUARANTINE_NUMERATOR
<quarantine_size> >= <heap size> * ----------------------
QUARANTINE_DENOMINATOR
The default values are QUARANTINE_NUMERATOR=1 and
QUARANTINE_DENOMINATOR=4 respectively giving the same
behavior as the previous default QUARANTINE_RATIO=4.
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The environmental variables _RUNTIME_QUARANTINE_NUMERATOR and _RUNTIME_QUARANTINE_DENOMINATOR can now override compiled defaults for QUARANTINE_NUMERATOR and QUARANTINE_DENOMINATOR.
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markjdb
approved these changes
Apr 2, 2025
| @@ -1316,6 +1321,33 @@ mrs_init_impl_locked(void) | |||
| exit(7); | |||
| } | |||
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| if (!issetugid()) { | |||
| char *envstr, *end; | |||
| if ((envstr = getenv(MALLOC_QUARANTINE_DENOMINATOR_ENV)) != | |||
There was a problem hiding this comment.
BTW we have secure_getenv() in libc now, effectively a helper for if (!issetugid()) { var = getenv(...); ... }.
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Replace QUARANTINE_RATIO with a fraction set by QUARANTINE_NUMERATOR and QUARANTINE_DENOMINATOR.