site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com On Jul 29, 2006, at 12:42 PM, Jonas Maebe wrote: On 26 Jul 2006, at 22:21, Quinn wrote: = Mike _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... Also, for maximum effectiveness, you should ensure that your disk I/Os are to a page aligned buffer, at a page aligned offset with the file, and are an even multiple of a page in length. A similar question just popped up on perfoptimization-dev. If Microsoft and Adobe aren't filing bugs over this, it might nevertheless be interesting for some Apple engineers evaluate the way the cache flushing daemon (update) behaves, since it's apparently killing performance for various apps (possibly including things like Entourage, which I think should not require something like F_NOCACHE for its mail database). See http://lists.apple.com/archives/perfoptimization-dev/2006/Jul/ msg00047.html and follow-ups, in particular http://lists.apple.com/ archives/perfoptimization-dev/2006/Jul/msg00056.html and http:// lists.apple.com/archives/perfoptimization-dev/2006/Jul/msg00057.html Without having a chance to analyse the actual example, I think you're blowing this a little out of proportion. It's quite difficult to generate "2-3 minutes" worth of dirty file data without having any of it pushed out, and the message claiming that dirty data is pushed synchronously every 30 seconds is completely incorrect. It *is* possible to find yourself blocked waiting for data to be flushed if you attempt to flush twice in a row; the second flush request wants the same lock that is held by the flush operation that was kicked off by the first request. This is by design, making it possible to synchronously wait for an asynchronous flush, however this operation is only per-file, not system-wide. The way in which dirty file data is flushed is well understood by Apple, and the MBU has good communication into the organisation. This email sent to site_archiver@lists.apple.com