获得CPU时间在OS X [英] Getting CPU time in OS X
问题描述
我对OS X的一个Objective-C的应用程序，比较两个sqlite的DB的，并产生一个JSON格式的差异。该数据库是相当大（10,000项与许多领域）。有时这个应用中约为55秒运行（使用CPU的95％）。有时需要约8分钟（使用CPU的12％）。这是使用相同的DB的。当它仅使用CPU的一小部分，其余是可用的。似乎没有被任何服用优先的处理。加入好看-20的命令，似乎保证我得到的CPU使用率。我的问题是
-
如果没有其他正在使用的CPU为什么
我的应用程序没有利用
呢？ -
有什么我可以做
编程改变这种？ -
有什么我可以做的OS X操作系统
改变呢？
问1：
一直以来，我认为，你从磁盘数据库读取，你是不是因为你的code被阻塞在磁盘读取，充分利用CPU的。在Mac OS X上有很多东西在后台运行，不使用大量的CPU时间，但并散发出大量的磁盘的读操作，就像聚光灯下。
问题2：
或许不会，除了最有效地利用磁盘访问成为可能。
问题3：
关闭正在访问磁盘的任何其他进程。这包括许多系统进程，你真的不应该关机，所以我不认为有什么可以做，在这里除了尝试运行它达尔文没有所有的Mac OS X的空想。
I have an objective-c application for OS X that compares two sqlite DB's and produces a diff in json format. The db are quite large (10,000 items with many fields). Sometimes this applications runs in about 55 sec(using 95% of the cpu). Sometimes it takes around 8 min (using 12% of the cpu). This is with the same DB's. When it is only using a small portion of the cpu the rest is available. There does not appear to be anything taking priority over the process. Adding "nice -20" on the command seems to assure I get the cpu usage. My questions are
If nothing else is using the cpu why does my app not take advantage of it?
Is there something I can do programatically to change this?
Is there something I can do to OS X to change this?
Question 1:
Since, I assume, you have to read in the databases from disk, you aren't making full use of the CPU because your code is blocking on disk reads. On Mac OS X there is a lot of stuff running in the background that doesn't use a lot of CPU time but does send out a lot of disk reads, like Spotlight.
Question 2:
Probably not, other than make the most efficient use of disk access possible.
Question 3:
Shut down any other processes that are accessing the disk. This includes many system processes that you really shouldn't shut down, so I don't think there's much you can do here other than try running it on Darwin without all the Mac OS X fanciness.
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