作为一些冷缓存时间的一部分,我试图释放OS缓存。该内核文档(检索2019日)说:
drop_caches
Writing to this will cause the kernel to drop clean caches, as well as
reclaimable slab objects like dentries and inodes. Once dropped, their
memory becomes free.
To free pagecache:
echo 1 > /proc/sys/vm/drop_caches
To free reclaimable slab objects (includes dentries and inodes):
echo 2 > /proc/sys/vm/drop_caches
To free slab objects and pagecache:
echo 3 > /proc/sys/vm/drop_caches
This is a non-destructive operation and will not free any dirty objects.
To increase the number of objects freed by this operation, the user may run
`sync' prior to writing to /proc/sys/vm/drop_caches. This will minimize the
number of dirty objects on the system and create more candidates to be
dropped.
This file is not a means to control the growth of the various kernel caches
(inodes, dentries, pagecache, etc...) These objects are automatically
reclaimed by the kernel when memory is needed elsewhere on the system.
Use of this file can cause performance problems. Since it discards cached
objects, it may cost a significant amount of I/O and CPU to recreate the
dropped objects, especially if they were under heavy use. Because of this,
use outside of a testing or debugging environment is not recommended.
You may see informational messages in your kernel log when this file is
used:
cat (1234): drop_caches: 3
These are informational only. They do not mean that anything is wrong
with your system. To disable them, echo 4 (bit 3) into drop_caches.
我对细节有些粗略。跑步
echo 3 > /proc/sys/vm/drop_caches
释放页面缓存,牙科和索引节点。好。
因此,如果我希望系统再次正常开始缓存,是否需要先将其重置为0?我的系统当前将值设置为0,我认为这是默认值。还是会自行重置?我在这里至少看到两种可能性,但我不确定哪一种是正确的:
echo 3 > /proc/sys/vm/drop_caches
释放页面缓存,牙科和索引节点。然后,系统立即再次开始缓存。我不确定在/proc/sys/vm/drop_caches
这种情况下我期望该值做什么。几乎立即回到0?如果
/proc/sys/vm/drop_caches
设置为3,则系统在重置为0之前不会进行任何内存缓存。
哪种情况是正确的?
天啊!@VolkerSiegel我已经擦洗了Interweb数小时,并随机找到了您的评论。尝试了一下,效果很好!感谢您添加此小技巧。我不想劫持这个问题,但是如果这不是不合适的话,我想请教一下。当我将sshpass与一起使用时
—
harperville '16
sudo -i && echo 3 > /proc/sys/vm/drop_caches
,出现错误:stdin: is not a tty
。使用您的“ sudo”方法有效。为什么?
@harperville提出问题;这几乎可以肯定是一个不相关的问题。
—
Faheem Mitha
@harperville是的-这是一个很好的问题-有一个有趣的答案,请单独询问!那让我知道 还是您想让我自己问一个问题然后回答?
—
Volker Siegel
echo 3 | sudo tee /proc/sys/vm/drop_caches