turn off logs?

James Cameron quozl at laptop.org
Tue Feb 8 00:06:48 EST 2011

On Mon, Feb 07, 2011 at 11:18:02PM -0500, Martin Langhoff wrote:
> On Mon, Feb 7, 2011 at 7:57 PM, James Cameron <quozl at laptop.org> wrote:
> > Even with the buffered I/O, occasional writes will stall, resulting
> > in activity code stall.
> In normal (!debug) mode logs are *tiny*.  We have the right tradeoff.

No, I think you misunderstand.  It doesn't matter how tiny the writes
are, or how few there are, they still happen, and since they are to a
filesystem, the kernel has the right to convert the write into an
effectively synchronous operation.  This happens when there is even
trivial memory pressure.  On XO-1.5, this hurts us badly, because of the
random write performance of the internal storage.

> > Future redesign might be to pipe the stdout/stderr to the Sugar shell
> > and have it write it to filesystem only if the activity fails. ?;-)
> NO. That would be very bad. Activities can bring Sugar down (just
> spotted one nasty that brings down X.org), and then you have no hint.

If the writes were to a buffered pipe, as part of python's subprocess
implementation, then the writes won't be delayed, since the buffer is
already available.  The text from the activity would not be processed,
only written.  I don't see how this could bring Sugar down, please
provide more detail.  A separate disposable logger process might
alleviate your fear.  It's something for Sugar Labs to consider.  In the
meanwhile we might log to tmpfs, with periodic rsync to storage.

James Cameron

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