The tag has no wiki summary.

learn more… | top users | synonyms

2
votes
1answer
473 views

How to cache all internet downloads

I am currently running Ubuntu 12.04. How would I go about caching all downloads? And if Linux does not have this built in, then what are good tools for this? Please note that this isn't a browser ...
3
votes
1answer
1k views

AIX 6.1 JFS2 Oracle files system, not using much files system cache

I am running Oracle database on AIX 6.1, Oracle using JFS2 file systems. Maxperm is set to 90%. This is busy database server, but it is not using the file system cache (less then 2%). The system has ...
3
votes
2answers
73 views

How to get size of data that haven't been written to disk yet?

In some programs percentage of copying large files get to 100% very fast and then I'm waiting much more before it goes next step. It's caused by buffer. How to I see amount of data that are going to ...
1
vote
2answers
2k views

How to bypass youtube's local cache?

Youtube performance here in Brazil has been terrible lately. Checking my browser's activity I can see that my ISP has a local Youtube cache and serves videos in 1.7 MB chunks. Talking to some friends ...
1
vote
4answers
4k views

How to clean up the RAM memory that is being used as cache memory?

My processor is using a big part of my RAM memory as cache and I want to clean it up because of that; will it prejudice something?
2
votes
1answer
223 views

How to utilize extended attributes for image preview?

Is there any file browsers for Linux that cache image previews, just like Windows Explorer cache them to a file named Thumbs.db? As in the latest ext3/4 filesystems, an inode can hold extended ...
0
votes
0answers
101 views

Real copy to Android device

When i copy files to the Android phone, they are copied to some cache, but they aren't written. I don't like it, because i don't know what is done. I've tried these methods: copying via thunar file ...
2
votes
1answer
379 views

Running a query without the OS cache

I want to emulate a client site who doesn't have much caching because they have so much I/O all the time. I want to run a SQL query on my machine (on my VM to be precise) with the same limitations ...
4
votes
3answers
348 views

Does bash have a built in caching command available (sort of like mktemp or sponge)?

I'm using the amazon ec2 command line tools, and the ec2-describe-instances tool is a little painful because of the 2-5 seconds it requires to make the request and display the output. I'm looking ...
11
votes
1answer
1k views

Is disabling barriers for ext4 safe on a laptop with battery?

The manual page says about the barrier option for ext4: Write barriers enforce proper on-disk ordering of journal commits, making volatile disk write caches safe to use, at some performance ...
4
votes
1answer
563 views

Drop a specific file from the Linux filesystem cache?

I know I can drop everything from the Linux filesystem cache, but is there a way to drop just one specific file? Or prevent a file from being cached? Or tell a process not to cache any files it ...
2
votes
2answers
457 views

mbcache documentation

I want to experiment with mbcache kernel module, but I'm having trouble finding the documentation for it. If I understood correctly, mbcache allows the use of a fast SSD disk to act as a transparent ...
8
votes
2answers
838 views

lshw and lscpu disagree on caches - which is right?

I am trying to find out specifics about caches (in particular which caches are shared between cores and which are not) and have stumpled onto a inconsistency. sudo lshw says *-cache:0 ...
3
votes
1answer
1k views

What is the buffers column in the output from free?

These questions briefly list the format of the free command, noting that buffers is kernel memory that must be written out to disk and cache is file data that does not need to be written disk. On my ...
3
votes
2answers
338 views

`free`: output format

I use free to get the amount of free space on some of my servers. Its output is something like: $ free -m total used free shared buffers cached Mem: 374 ...
2
votes
3answers
726 views

delayed write in operating file system

I read in some papers about NFS and Sprite that a system can use delayed writes when a client writes something to the server. I would like to know what is the purpose of this technique?
1
vote
2answers
351 views

Embedded device: How to do raw reads and write to flash (emmc/movinand) bypassing file system cache

I have an embedded device with a flash memory running linux. I want to do raw read writes on the flash part but I also want to avoid any file system cache. How can I do this? Any pointers?
2
votes
1answer
391 views

dav2fs caching problem on Debian Squeeze

I have apache/mod_dav and davfs2 all on the same host. davfs2 is used to mount what Apache is serving to the local filesystem - a sort of loopback. The purpose is that the content of the files served ...
2
votes
3answers
443 views

Is there a way to tell the system to keep a folder to reside in memory?

I'm developing a Java EE web application and I'm trying to speed up the testing process. To do so I was wondering if there is a way to tell the system to keep my build folder in system memory?
9
votes
4answers
847 views

Is there a way to sync only one partition?

Is there a way to sync only one partition instead of all partitions? Something like "sync /dev/sdc1".
6
votes
1answer
14k views

How to read the local DNS cache contents?

I know that on Windows I can issue ipconfig /displaydns and I see the local DNS's cache content. How can I list the DNS's cache content in Linux? I would like to get as much as cross-distro solution ...
3
votes
2answers
2k views

/proc/cpuinfo “cache” category: L1, L2 or total?

When I look in /proc/cpuinfo, one of the lines tells me I have 6144 KB of cache. Is this L1 cache, L2 cache, or the sum of both of them? In any case, how do I find out how much L1 and L2 cache my ...
5
votes
1answer
7k views

Is there a command which will force Linux to flush cache of one file on an NFS share?

Related to this question on StackOverflow, I am wondering if there is a way for me to flush the NFS cache / force Linux to see the most up-to-date copy of a file that's on an NFS share. I have a ...
18
votes
4answers
17k views

Can I safely remove /var/cache?

I am running out of disk space and noted that I have a large /var/cache directory. Can I safely remove this? (using Arch Linux, BTW).
1
vote
3answers
1k views

Increasing the size limit for /var/cache/apt/archives

I have 2 systems running Debian at home and I am trying to minimize the bandwidth use while upgrading the packages. How can I increase the size limit of the cache, so that I could just copy the ...
5
votes
2answers
5k views

Cleancache vs zram?

I have an old laptop here with only 512 MB of RAM. Since a few kernel releases, I am using zram to convert 256 MB of it to a compressed ramdisk which is then used as swap. This has proved to be very ...
1
vote
0answers
916 views

What is meant by cache aliasing? [closed]

What is the meant by cache aliasing? I searched around some, but wasn't satisfied with the answers I found. I also saw two associated terms, instruction cache aliasing & data cache aliasing. ...
2
votes
0answers
540 views

Linux kernel slab usage growing on embedded system

I'm in the process of QA/debugging a project on a custom embedded linux system. The problem we're VERY tight on memory, and even a couple megs can cause issues with our software. What I'm seeing ...
4
votes
1answer
2k views

What options are there for tuning Linux file system caching?

What various types of caching are possible in the ext3 file system and how can their values be changed using system calls or other methods? I don't want to use commands or tools.
16
votes
7answers
4k views

Linux equivalent to ReadyBoost?

Is there a kernel module or some other patch or something similar to Windows' ReadyBoost? Basically I'm looking for something that allows disk reads to be cached on a Flash drive.
1
vote
1answer
576 views

What is excessive swapping

This post led me to ask that question. Cache contention On a large site, if you are using MyISAM, contention occurs in the database tables when the cache is forced to clear after a node ...
25
votes
3answers
2k views

Does grep use a cache to speed up the searches?

I have noticed that subsequent runs of grep on the same query (and also a different query, but on the same file) are much faster than the first run (the effect is easily noticeable when searching ...
8
votes
5answers
4k views

How to cache or otherwise speed up `du` summaries?

We have a large file system on which a full du (disk usage) summary takes over two minutes. I'd like to find a way to speed up a disk usage summary for arbitrary directories on that file system. For ...
7
votes
2answers
1k views

How to time grep commands accurately?

I want to compare the speed of these two commands: grep pattern1 files* grep pattern2 files* Unfortunately, the first grep reads much of files* into memory buffers, so the second grep runs ...
15
votes
4answers
13k views

Where are stored the Youtube videos cache in Google Chrome?

Google Chrome used to store YouTube videos in /tmp, but not for the last two versions. Nor could I find those files in ~/.cache/google-chrome. Googling for this query produces Windows-specific ...
53
votes
2answers
11k views

How do I clear Bash's cache of paths to executables?

When I execute a program without specifying the full path to the executable, and Bash must search the directories in $PATH to find the binary, it seems that Bash remembers the path in some sort of ...
5
votes
1answer
355 views

Why doesn't dm-crypt handle write barriers properly?

One of the well-known properties of dm-crypt is that it does not handle write barriers properly and hence it requires turning off on-drive write cache to prevent corruption of filesystems. As far as I ...
0
votes
2answers
174 views

Caching bugzilla webpages for offline use

I have a long wifi free journey ahead of me and I would like to continue to productively review bugs even without the ability to change them. Is there an easy way to cache all the pages generated ...
7
votes
3answers
478 views

Why does it makes sense to cache swap?

It sounds quite counter-productive to me to cache pages that are swapped out. If you swap pages in, what is the advantage to first cache them in memory, only to have to than move them to the right ...
6
votes
5answers
12k views

dns queries not using nscd for caching

I'm trying to use nscd (Nameservices Cache Daemon) to cache dns locally so I can stop using bind to do it. I've gotten it started and ntpd seems to attempt to use it. But everything else for hosts ...