Comment by wbl
8 years ago
How about this idea: free() zeros or unmaps all memory it allocated. This shouldn't fault. The OS zeros pages when mapping them into the process space (which it should do anyway). I think that solves the problem.
8 years ago
How about this idea: free() zeros or unmaps all memory it allocated. This shouldn't fault. The OS zeros pages when mapping them into the process space (which it should do anyway). I think that solves the problem.
free() doesn't know what portion of the memory you allocated actually got written to. So for the model where a large, page-spanning buffer is allocated and only a small portion used, this approach causes many unnecessary page faults at free () time as it tries to zero out lots of memory that was never used or paged in at all.
Large buffers just get unmmaped so the OS can fix that problem.