On: Unix V5, OpenBSD, Plan 9, FreeBSD, and GNU impleme...

[cpeterso]

Or just declare a large static buffer.

[tedunangst → cpeterso]

"Nobody will ever echo this much data!"

[tmp43522 → tedunangst]

It's actually not a bad suggestion

    #define BUF_INITIAL 1024
    char buf[BUF_INITIAL];
    
    int main(int argc, char** argv)
    {
        char* p;
        ...
        p = len > BUF_INITIAL ? malloc(len) : buf;
        ...
        write(1, p, len);
        ...
    }

[cpeterso → tmp43522]

djb's allocator alloc() does this. He preallocates a 4 KB static buffer before hitting system malloc(). Avoiding the overhead of malloc() is pretty important for the performance of systems like qmail that fork many small processes.

[tedunangst → cpeterso]

That's ridiculous. The overhead of fork is about a bajillion times higher than malloc.

[adestefan → tedunangst]

With a COW fork() I bet it's smaller. I smell a test coming on, but alas it's late here and I'm going to bed.

I'm also guessing that 4k was chosen because a malloc() of 1 page is faster than a malloc() of >1 page. Of course that's with the assumption that the systems use a 4k page size.

[aidenn0 → tedunangst]

Are you sure? I'd bet it's greater, I'd not bet that it's an order of magnitude better, fork() has been optimized a lot more than brk().

[sliverstorm → cpeterso]

Many small processes? How many?

4 KB * (many) could be frightening.

[jff → sliverstorm]

If your system has 32,000 processes and you allocate 4 KB to each of them... that's 128 MB. I'm not crapping my pants at that figure because even the oldest machine in my office, an old Thinkpad, has 2 GB of RAM.

[GreySyntax → tedunangst]

Oh wait they will