drivers/char/random.c:write_pool() -- cond_resched needed? - Kernel

This is a discussion on drivers/char/random.c:write_pool() -- cond_resched needed? - Kernel ; In write_pool(), isn't cond_resched() needed after call to add_entropy_words() because otherwise there can be large latencies (think of command "dd if=/dev/zero of=/dev/random bs=100000000" ) ? -- Do what you love because life is too short for anything else. - To ...

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Thread: drivers/char/random.c:write_pool() -- cond_resched needed?

  1. drivers/char/random.c:write_pool() -- cond_resched needed?

    In write_pool(), isn't cond_resched() needed after call to
    add_entropy_words() because otherwise there can be large latencies
    (think of command "dd if=/dev/zero of=/dev/random bs=100000000" ) ?

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    Do what you love because life is too short for anything else.

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  2. Re: drivers/char/random.c:write_pool() -- cond_resched needed?

    On Fri, Nov 30, 2007 at 11:58:10PM +0200, Sami Farin wrote:
    > In write_pool(), isn't cond_resched() needed after call to
    > add_entropy_words() because otherwise there can be large latencies
    > (think of command "dd if=/dev/zero of=/dev/random bs=100000000" ) ?


    Yes, looks like you're right.

    Reduce latency for large writes to /dev/[u]random

    Signed-off-by: Matt Mackall

    diff -r c60016ba6237 drivers/char/random.c
    --- a/drivers/char/random.c Tue Nov 13 09:09:36 2007 -0800
    +++ b/drivers/char/random.c Mon Dec 03 12:48:30 2007 -0600
    @@ -1041,6 +1041,7 @@ write_pool(struct entropy_store *r, cons
    p += bytes;

    add_entropy_words(r, buf, (bytes + 3) / 4);
    + cond_resched();
    }

    return 0;


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