cache is a component that stores data so future requests for that data can be served faster; the data stored in a cache might be the results of an earlier computation, or the duplicates of data stored elsewhere.

learn more… | top users | synonyms

3
votes
1answer
32 views

Is it a good idea to put ~/.cache in a tmpfs?

I'm concerned about the ~/.cache directory for two reasons : it causes a lot of writes on my SSD unnecessarily, and it contains informations (like image thumbnails) about files in encrypted containers ...
0
votes
1answer
39 views

Vim saved file not updating on webpage

I am attempting to update an HTML file on my server, but when I do so it doesn't appear to be updating, but rather, serves an old copy instead. I went through the usual process of pressing :w and ...
0
votes
0answers
18 views

stop dm-cache from caching temporarily

I am want to benchmark my system(Centos) IOPS with dm-cache and without dm-cache.I have taken benchmark result for my system dm-cache .Now I want dm-cache to stop temporary so that I can take ...
1
vote
1answer
13 views

Error while installing Bcache on centOS

I am trying to setup Bcache on my existing system(Its risky,but we are not worried about losing any data ) . So my make and make install works proper but when I run the command make-bcache i receive ...
0
votes
1answer
55 views

device-mapper: reload ioctl on cache1 failed: Device or resource busy

When I run the below command while setting up dm-cache on my CentOS system, I receive the error: device-mapper: reload ioctl on cache1 failed: Device or resource busy Command failed Command is: ...
1
vote
0answers
10 views

Which is the correct dm-cache version

I am trying to install dm-cache on my CentOS machine. Which dm-cache version should I use. I read on wikipedia as below: Another dm-cache project with similar goals was announced by Eric Van ...
0
votes
0answers
35 views

device-mapper error while setup of dm-cache

I am trying to setup dmcache using the tutorial https://wiki.mikejung.biz/Dmcache When I run the command `dmsetup create home-cached --table '0 976771120 cache /dev/mapper/ssd-metadata ...
3
votes
2answers
61 views

Defer *all* disk writes, keep them in memory

How to temporarily stop synchronizing of dirty data with disk, instead just keeping it in memory. Clarification: I want to sync it later.
0
votes
1answer
38 views

How to deactivate linux page/disk cache?

I would like to turn off the disk / storage cache on Raspbian. I have done a serie of benchmarks on the microSD (http://jgp.net/microsd-card-performance-raspberry-pi/) but some people recommended I do ...
0
votes
1answer
27 views

ncmpcpp is damaged after experienced a crash

My problem appeared with ncmpcpp the console music player. I've used ncmpcpp to open a .pls file from the Browser window and it crashed perhaps due to encoding problems. Since then, Every time I ...
3
votes
0answers
111 views

How to interpret perf -e cache-misses:pp?

I find the behavior of perf top -e cache-misses:pp -p <my_pid> quite confusing. I own an Intel i5-3230M, running kernel 4.4.5 64 bit. If I just run that commmand, I get basically no samples ...
0
votes
1answer
119 views

How can I clear my cache?

I'm running a live CD linux distro and I'm getting out of memory exceptions. >java -version #Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x0000000646e00000, 264241152, 0) ...
0
votes
1answer
35 views

-/+ buffers/cache & Swap

When should the usage of swap get started? or How do I know that my swap is being used? At least some times if not always, considering the default swappiness of 60 Also, why does free offer to omit ...
0
votes
1answer
30 views

How does the diff command handle caching?

I became curious when I was diffing two large (>326MB) files, and noticed that the second run took much less time than the first. This was frustrating, since I was trying to time the second run, to ...
1
vote
0answers
49 views

bcache not working as expected with ramdisk as cache device

I was trying out bcache but i don't have an SSD so wanted to use free memory as a substitute. As ramdisk is listed in /proc/devices as block device i assumed this would work OK but with below simple ...
0
votes
1answer
23 views

Is the iSCSI block device having client side-read cache (if yes how to disable)?

I have a remote block device with the test ext4 filesystem image. On the iSCSI initiator side, I have this device detected as let's say /dev/sdb. I am not mounting this filesystem but instead I use ...
1
vote
1answer
54 views

Using terminal to reset icon cache - which method?

I've been trying to find out how to reset the icon cache on my MacBook, and two methods seem to always be suggested. However, the two approaches differ slightly in the third line. Method 1 sudo find ...
0
votes
0answers
43 views

SSD + HDD performance from power on

I'm planing to buy a new laptop with a 128GB SSD and a 1TB HDD. And I would like to have reliability, performance and storage space from power up and during the whole runing time. During the running ...
4
votes
0answers
115 views

LVM cache and TRIM

I have set up LVM to cache a logical volume (located on an HDD) on a partition of an SSD (in writeback mode if this matters). As far as I can tell, this works correctly and the cache uses all ...
3
votes
0answers
68 views

How to cache block devices (for device mapper)?

problem / observed effect It seems that the page cache ignores block devices which are not opened. And worse: Reads from device mapper (DM) devices which use a cached device are not cached at all ...
1
vote
0answers
44 views

One SSD cache for two partitions on two separate disks?

I have two hard drives: one for my operating system and the other for other data. I recently bought an SSD drive that I would like to use an LVM cache for those two devices. The problem is that I ...
5
votes
0answers
178 views

Why are slab objects not reclaimed automatically

Everyday after a full system backup, various programs are failing with read errors until I run echo 2 > /proc/sys/vm/drop_caches to free reclaimable slab objects. For example, here's the output of ...
1
vote
2answers
61 views

how does o_sync trigger pdflush?

When I write using o_sync, the write call returns once the data has been written to the disk. But how does o_sync force Linux to write the data to disk? Normally you would have to wait a maximum of ...
1
vote
0answers
197 views

OpenLDAP as a Proxy cache only, no local database

I am trying to get a local LDAP proxy cache running. The idea is this: Currently a computer (A) is sending all ldap requests to a remote ldap server (L) Instead of that, there should be a proxy ...
0
votes
0answers
26 views

SSD as write target during reads

I have a real-time application which always writes data to a RAID 10 HDD configuration in a sequential manner at around ~50 MB/s. It uses mmap and writing should never be blocked due to waiting I/O. ...
0
votes
1answer
165 views

how to increase cache memory in centos

I have been facing a insuffient space in "/var/cache/yum" directory. due to this my gui of centos crashes.i want to increase the size of cache directory. also want to know the actual size of cache ...
2
votes
0answers
26 views

Which subsystem caches file reads?

I am trying to understand how exactly file reads are served from Page Cache. This will be useful when I will be implementing my own filesystem in the kernel. Is file content cached by VFS or ...
1
vote
1answer
102 views

Linux top -n 1 Command doesn't get update

I'm calling the Linux top -n 1 -b command from a Qt application to get the free CPU percentage. This application calls this command every 3 seconds, but the CPU usage seems to be updated only the ...
1
vote
1answer
39 views

Reset Bash's memory used for auto-complete

After renaming a file to a similar name, I noticed TAB was still completing the old filename (if it matched the letters so far) and not showing the new one. No matter how many letters I typed, it ...
2
votes
1answer
30 views

Is partition created by dd (and cached) instantly available for writing

I'm creating a partition (from backup) with dd and need to know if there is a need of some sort of sync/timeout before I can access it. As I know data may be cached in dirty pages. But what if I ...
0
votes
0answers
55 views

How to configure some proxy like Squid to download specific URL only once?

I have read article about Windows 10 spying my activity and blocked all mentioned addresses on my router's firewall. This included addresses az361816.vo.msecnd.net and az512334.vo.msecnd.net ...
1
vote
0answers
28 views

what is left inside the cache even after clearing the page cache data?

I was trying to clear the cache using echo 3 > /proc/sys/vm/drop_caches Even after performing the above operation there remain some space inside the cache? When I check with free -m around it ...
1
vote
1answer
339 views

Using readahead in Debian Jessie

The article BootProcessSpeedup on the Debian Wiki lists a tip to speed up boot time. It says to install readahead and then #touch /etc/readahead/profile-once. It seems like an outdated article, ...
1
vote
1answer
61 views

Linux Gateway as Download Accelerator like IPCop's

We're running dnsmasq on a linux box inside our network for DHCP and DNS. I would like to add a download accelerator like IPCop's (http://blockouttraffic.de/ua_index.php) but without having IPCop as ...
4
votes
1answer
422 views

How does Linux handle block devices?

Today I learned that FreeBSD removed support for block devices entirely. While reading their rational for the decision I came across this: Block devices are disk devices for which the kernel ...
1
vote
2answers
494 views

Force dig to forget records

I would like to let dig always forget a DNS record. I mean if I do dig yahoo.com then I have a record back in with ttl for 1790 seconds. Even if I have no cache service installed, next time i do the ...
5
votes
2answers
177 views

How to enable package caching in dnf?

I started using fedora 22 and started learning dnf only to find out about two annoying facts: Almost every time I install or upgrade anything it has to rebuild the whole repository metadata cache ...
0
votes
1answer
91 views

why does my Ubuntu Virtual Machine slow down after a number of searches, and builds?

I recently learned that my Ubuntu Linux file system may cache the result of some commands such as searches, sorts, and perhaps build commands such as make. I run Ubuntu in a VM, and although I have ...
1
vote
0answers
18 views

CVMFS file access slow, although file is in cache

I have a directory in which there is a symlink to a file on CVMFS. When I first boot up, and do ls, it takes a long time (~a minute). The reason is that ls does fstat on each file to determine what ...
3
votes
1answer
212 views

How to run free command by crontab

I want to run this command: free && sync && echo 3 > /proc/sys/vm/drop_caches && free -m by cron. That way I can free my RAM and cache in an Ubuntu system. I'm using ...
1
vote
0answers
142 views

Opcache and shared memory issue

I installed zend_opcache on my server box , but I can not increase opcache.memory_consumption over 1600 . (example : 2048) . after increase following error occur in server : Fatal Error Fatal Error ...
0
votes
0answers
87 views

Will btrfs snapshots ever share page cache?

It's common to run multiple container images based on the same parent. In theory you should be able to share page cache between these containers automatically. E.g. some of the code in shared ...
3
votes
1answer
50 views

Directory traversal cache eviction despite having plenty of memory?

I have a huge Mercurial repository (take a guess how many directories it has -- it's gonna be more than you guessed). The time taken to do basic repository operations is heavily dependent on whether ...
3
votes
0answers
53 views

What could cause dropping cache to be extremely slow on a large cluster?

I'm attempting to time file I/O on my disks. In order to make sure all the I/O is happening off the hard drives and not from ram, before I time any read, I run a drop cache command. Specifically, I ...
-1
votes
1answer
245 views

What is ~/.cache/weather.xml?

I use a clock-date-weather conky and I noticed that it is related to the file ~/.cache/weather.xml. I am curious: was this file created by conky or by what other program? Is it present on the system ...
1
vote
0answers
431 views

ssd caching in loop device on btrfs

I have an ssd and 2TB hard disk. The ssd is used for the root filesystem which uses only around 20G of the 120G available. Is there a way to use an image/loop on the root filesystem (btrfs) as a cache ...
16
votes
3answers
2k views

Is it safe to remove ~/.cache?

When I scanned my $HOME directory with baobab (Disk Usage Analyzer), I found that ~/.cache is consuming about half a GB. I also tried to restart and again check size but no difference. So, I am ...
3
votes
0answers
62 views

Is posix_fadvice / POSIX_FADV_DONTNEED functional in Linux?

If I am doing once only scanning across big files then do I need to worry about impact on the page cache or does the OS take care to avoid my scan causing pointless churn in the page cache. I want to ...
3
votes
1answer
170 views

Linux doesn't drop FS Caches. Instead Memory starts Swapping

I'm quite confused about this behaviour of linux memory caching. total used free shared buffers cached Mem: 15953 14188 1765 64 ...
6
votes
1answer
273 views

Limit the inode cache used by a command

I want to run a task with limits on the kernel objects that they will indirectly trigger. Note that this is not about the memory, threads, etc. used by the application, but about memory used by the ...