blocks|key|1642100|text|使用SysInternal的RAMMap+app。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1642101|​|1642102|📷|atomic|1642103|1642104|Empty+/+Empty+Standby+List菜单选项将清除Windows文件缓存。|1642105|entityMap|0|LINK|mutability|MUTABLE|url|http://technet.microsoft.com/en-us/sysinternals/ff700229.aspx|1|IMAGE|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/53b9268c688eb6dcc65f96d8a4d2b9e3.png|imageAlt^0|E|A|0|0|0|0|1|1|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@$A|10|B|11|1|12]]|C|$]]|$1|D|3|E|5|6|7|13|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|14|8|@]|9|@$A|15|B|16|1|17]]|C|$]]|$1|I|3|E|5|6|7|18|8|@]|9|@]|C|$]]|$1|J|3|K|5|6|7|19|8|@]|9|@]|C|$]]|$1|L|3|-4|5|6|7|1A|8|@]|9|@]|C|$]]]|M|$N|$5|O|P|Q|C|$R|S]]|T|$5|U|P|V|C|$W|X|Y|-4]]]]

Use SysInternal's <a href="http://technet.microsoft.com/en-us/sysinternals/ff700229.aspx">RAMMap app</a>.

<img src="https://i.stack.imgur.com/EuOmF.png" alt="rammap empty standby">

The Empty / Empty Standby List menu option will clear the Windows file cache.

blocks|key|1427191|text|对于Windows+XP，您应该能够通过使用带有FILE_FLAG_NO_BUFFERING选项的CreateFile打开文件，然后关闭句柄来清除特定文件的缓存。这并没有文档记录，我不知道它是否可以在更高版本的Windows上运行，但我很久以前在编写测试代码来比较文件压缩库时就用过了。我不记得是读访问还是写访问影响了这个技巧。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1427192|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

For Windows XP, you should be able to clear the cache for a specific file by opening the file using CreateFile with the FILE_FLAG_NO_BUFFERING options and then closing the handle. This isn't documented, and I don't know if it works on later versions of Windows, but I used this long ago when writing test code to compare file compression libraries. I don't recall if read or write access affected this trick.

blocks|key|1642125|text|+#include+<fcntl.h>

int+posix_fadvise(int+fd,+off_t+offset,+off_t+len,+int+advice);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1642126|带有建议选项POSIX_FADV_DONTNEED|unstyled|offset|length|style|CODE|1642127|++The+specified+data+will+not+be+accessed+in+the+near+future.|1642128|entityMap^0|0|6|J|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|P|8|@$G|Q|H|R|I|J]]|9|@]|A|$]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$B|C]]|$1|M|3|-4|5|F|7|T|8|@]|9|@]|A|$]]]|N|$]]

<pre><code> #include &lt;fcntl.h&gt;

int posix_fadvise(int fd, off_t offset, off_t len, int advice);
</code></pre>

with advice option <code>POSIX_FADV_DONTNEED</code>: 
 The specified data will not be accessed in the near future.

blocks|key|1642182|text|要获得有关Windows+XP+Filesystem+Cache的更好视图-请尝试使用ATM+by+Tim+Murgent+-它允许您以更详细、更准确的视图查看文件系统缓存工作集大小和备用列表大小。对于Windows+XP+-由于V2和V3需要Server2003、Vista或更高版本，您需要可以下载here的自动柜员机的旧版本1。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1642183|您将观察到，尽管Sysinternals+Cacheset将减少“缓存WS最小值”，但实际数据仍然以备用列表的形式继续存在，可以在备用列表中使用它，直到它被其他数据替换为止。然后使用MemAlloc、flushmem+by+Chad+Austin或Windows+Server+2003+Resource+Kit+Tools中的Consume.exe等工具将其替换为其他内容。|1642184|entityMap|0|LINK|mutability|MUTABLE|url|http://www.tmurgent.com/Tools/ATM/Default.aspx|1|http://www.tmurgent.com/download/ATM_32bit_V2.zip|2|http://www.tmurgent.com/download/ATM_x86_3.0.zip|3|http://www.tmurgent.com/download/ATM32_01000000.zip|4|http://technet.microsoft.com/en-us/sysinternals/bb897561.aspx|5|http://www.soft.tahionic.com/download-memalloc/|6|http://chadaustin.me/2009/04/flushing-disk-cache/|7|http://www.microsoft.com/downloads/details.aspx?FamilyID=9D467A69-57FF-4AE7-96EE-B18C4790CFFD&displaylang=en^0|17|I|0|37|2|1|3A|2|2|47|4|3|0|8|L|4|2J|8|5|2S|N|6|3G|12|7|0^^$0|@$1|2|3|4|5|6|7|11|8|@]|9|@$A|12|B|13|1|14]|$A|15|B|16|1|17]|$A|18|B|19|1|1A]|$A|1B|B|1C|1|1D]]|C|$]]|$1|D|3|E|5|6|7|1E|8|@]|9|@$A|1F|B|1G|1|1H]|$A|1I|B|1J|1|1K]|$A|1L|B|1M|1|1N]|$A|1O|B|1P|1|1Q]]|C|$]]|$1|F|3|-4|5|6|7|1R|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]|N|$5|I|J|K|C|$L|O]]|P|$5|I|J|K|C|$L|Q]]|R|$5|I|J|K|C|$L|S]]|T|$5|I|J|K|C|$L|U]]|V|$5|I|J|K|C|$L|W]]|X|$5|I|J|K|C|$L|Y]]|Z|$5|I|J|K|C|$L|10]]]]

For a much better view of the Windows XP Filesystem Cache - try <a href="http://www.tmurgent.com/Tools/ATM/Default.aspx" rel="nofollow">ATM by Tim Murgent</a> - it allows you to see both the filesystem cache Working Set size and Standby List size in a more detailed and accurate view. For Windows XP - you need the old version 1 of ATM which is available for download <a href="http://www.tmurgent.com/download/ATM32_01000000.zip" rel="nofollow">here</a> since <a href="http://www.tmurgent.com/download/ATM_32bit_V2.zip" rel="nofollow">V2</a> and <a href="http://www.tmurgent.com/download/ATM_x86_3.0.zip" rel="nofollow">V3</a> require Server 2003,Vista, or higher.

You will observe that although <a href="http://technet.microsoft.com/en-us/sysinternals/bb897561.aspx" rel="nofollow">Sysinternals Cacheset</a> will reduce the "Cache WS Min" - the actual data still continues to exist in the form of Standby lists from where it can be used until it has been replaced with something else. To then replace it with something else use a tool such as <a href="http://www.soft.tahionic.com/download-memalloc/" rel="nofollow">MemAlloc</a> or <a href="http://chadaustin.me/2009/04/flushing-disk-cache/" rel="nofollow">flushmem by Chad Austin</a> or Consume.exe from the <a href="http://www.microsoft.com/downloads/details.aspx?FamilyID=9D467A69-57FF-4AE7-96EE-B18C4790CFFD&amp;displaylang=en" rel="nofollow">Windows Server 2003 Resource Kit Tools</a>.

blocks|key|1642227|text|因为这个问题也是针对Linux的，所以有一个相关的答案here。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1642228|命令行工具vmtouch允许在系统文件缓存中添加和删除文件和目录。|1642229|entityMap|0|LINK|mutability|MUTABLE|url|https://serverfault.com/q/43383/112550|1|https://hoytech.com/vmtouch/^0|R|4|0|0|5|7|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@$A|U|B|V|1|W]]|C|$]]|$1|F|3|-4|5|6|7|X|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]|N|$5|I|J|K|C|$L|O]]]]

As the question also asked for Linux, there is a related answer <a href="https://serverfault.com/q/43383/112550">here</a>.

The command line tool <a href="https://hoytech.com/vmtouch/" rel="nofollow noreferrer">vmtouch</a> allows for adding and removing files and directories from the system file cache, amongst other things.

blocks|key|1642260|text|有一个windows+API调用https://docs.microsoft.com/en-us/windows/desktop/api/memoryapi/nf-memoryapi-setsystemfilecachesize可以用来刷新文件系统缓存。它还可用于将缓存大小限制为一个非常小的值。看起来非常适合这类测试。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1642261|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.microsoft.com/en-us/windows/desktop/api/memoryapi/nf-memoryapi-setsystemfilecachesize^0|G|2Q|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

There's a windows API call <a href="https://docs.microsoft.com/en-us/windows/desktop/api/memoryapi/nf-memoryapi-setsystemfilecachesize" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/windows/desktop/api/memoryapi/nf-memoryapi-setsystemfilecachesize</a> that can be used to flush the file system cache. It can also be used to limit the cache size to a very small value. Looks perfect for these kinds of tests.

What tools or techniques can I use to remove cached file contents to prevent my performance results from being skewed? I believe I need to either completely clear, or selectively remove cached information about file and directory contents.

The application that I'm developing is a specialised compression utility, and is expected to do a lot of work reading and writing files that the operating system hasn't touched recently, and whose disk blocks are unlikely to be cached.

I wish to remove the variability I see in IO time when I repeat the task of profiling different strategies for doing the file processing work.

I'm primarily interested in solutions for Windows XP, as that is my main development machine, but I can also test using linux, and so am interested in answers for that environment too.

I tried SysInternals <a href="http://technet.microsoft.com/en-us/sysinternals/bb897561.aspx" rel="noreferrer">CacheSet</a>, but clicking "Clear" doesn't result in a measurable increase (restoration to timing after a cold-boot) in the time to re-read files I've just read a few times.

Clear file cache to repeat performance testing

命令行工具

文件系统

Windows

Linux

我可以使用什么工具或技术来删除缓存的文件内容，以防止我的性能结果被扭曲？我认为我需要完全清除或选择性地删除有关文件和目录内容的缓存信息。我正在开发的应用程序是一个专门的压缩实用程序，预计会做大量的工作来读取和写入文件，这些文件是操作系统最近没有接触过的，并且其磁盘块不太可能被缓存。当我重复分析执行文件处理工作的不同策略的任务时，我希望消除IO时间中的可变性。我主要对Windows XP的解决方案感

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