site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=oIO4j1jFHEaQGEMA9DLWmCxV10a/9YUeVBQ9go3MUo5OgWpCObOFYH55kcniOe3Mj2o7wbFGov3EEOze/B8dmtTgR/aAGhSYWKttwo6IOiMU4fpvmst9BqZuf/P2FeH9G6cLvDUMk97SsGPIkesT3i3PHhTowwMepmnSUXMhi8w= ; My commercial app has a ram cache system for image sequence playback; images can be tens of megabytes and there can be gigabytes of them. On OS X, when the RAM cache is large, it looks like the darwin pageout demon is activating prematurely, paging out part of the RAM cache preemptively to meet its free-space target, even though there is no competing demand. Consequently, the app thrashes catastrophically to its knees. The details of system activity seems to matter---I have two different possible display paths (CG and GL), one of which transiently allocates and frees an extra image buffer. The path that allocates/frees causes the machine to thrash at RAM cache sizes that the other path is unaffected by, even though the total consumption is about the same. I need to better understand/control this issue and develop countermeasures. I think OS X's preemptive pageout to maintain minimum free list (see http://developer.apple.com/documentation/Performance/Conceptual/ManagingMemo...) is counterproductive, vs waiting for actual free-space demand. I'm investigating what the free-space target is (how it is set) and whether it might be changed. The thing I've found so far is VM_V_FREE_TARGET in http://developer.apple.com/documentation/Darwin/Reference/ManPages/man3/sysc... If there's a command-line version that might be used to examine/change these, that would be nice to know. The minimal fix is clearly to ratchet down the maximum permissible ram cache size well under (50%?) the machine's actual physical size. Though this is undesirable, it probably is better than letting the UI go unusable. Or, can the task priority be raised---will that give my app priority competing for free and inactive pages? Even if OS X wants to grab some pages to maintain its free list, I need it to grab them from inactive processes, not the ones it thinks are inactive in my app. I'm thinking that "wiring" 80% of the RAM into my app is unwise. Other possibilities include some sort of RAM-tickling demon. Suggestions welcome. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... This email sent to site_archiver@lists.apple.com