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1
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2answers
524 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
443 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
599 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?
10
votes
4answers
1k 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
18k 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
3answers
3k 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 ...
6
votes
1answer
10k 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 ...
20
votes
4answers
25k 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 ...
8
votes
2answers
6k 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
990 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
686 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.
18
votes
7answers
5k 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
711 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 ...
27
votes
3answers
3k 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 ...
9
votes
5answers
6k 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
15k 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 ...
77
votes
3answers
16k 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
385 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
181 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 ...
8
votes
3answers
538 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 ...
7
votes
5answers
16k 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 ...