Questions tagged [cache]
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.
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Question on tuning file system cache in Linux UBIFS on MTD
I am working on an embedded Linux system, where kernel is 5.10.24, and UBIFS on MTD is used.
The testing team had a test, which writes a disk file (open, write, close in order), then powers system off....
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How to empty name cache on FreeBSD?
The name cache on FreeBSD is responsible for caching file names and their vnodes. It also provides a special database for hashing the contents of large directories.
I would like to know how to empty ...
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How to drop the contents of the block cache of a partition/drive in Linux?
(Moved from Stack Overflow.)
I have a simple backup process that copies a bunch of files to a USB flash drive. I want to verify that copying was successful by re-reading the flash drive and comparing ...
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Flashing a bootloader without the use of sync doesn't work [duplicate]
So some background I was scripting building an SD Card Image for the Anbernic RG350M device.
This involves flashing a boot loader to the image. See below.
dd if="./select_kernel/squashfs-root/...
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Is it possible to implement kvm/qemu VM guests and host connected through shared memory to collect and cache data between them
The configuration:
host: Ubuntu:20.04 OS
guest: Ubuntu20.04 OS
The two files use the 9p file system for interworking.
The mount command is as follows,
mount -t 9p -o trans=virtio tmp_shared /mnt -...
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Selectively exclude paths or filesystems from Linux disk read cache
The Linux kernel uses unused RAM for disk read caching. This is generally a good idea. But is there a mechanism to selectively exclude certain paths or mounted filesystems from this cache?
ZFS for ...
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How can I stop blocks, which a single Linux process reads, from being cached? [duplicate]
I have a troublesome virus-checking program that scans the entire filesystem overnight. However, this program causes all the valuable data to be evicted from the server's cache, resulting in ...
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How to clear all cache data of google-chrome by commands executed by a bash script?
In my lubuntu 18.04 distribution I have installed google-chrome version 114.
By a bash script, at every boots, Chrome is launched and connects to a specific URL. The URL is always the same, but ...
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How to test Buffer Cache in Pintos (Pintos Project 4)
I'm working on Pintos Project 4, specifically the Buffer Cache part.
I have completed the code, but I am unsure how to test whether it is functioning correctly.
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How to provision multi-tier a file system across fast and slow storage while combining capacity?
I'm hunting for a way to utilise a slow 500GB magnetic HDD alongside a fast 500GB SSD.
I'd like to end up with a reasonable fraction of the two combined [hopefully > 800GB] in terms of capacity, ...
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Do we really need NSCD service running? What are the pros and cons?
We have a pretty mixed environment in terms of operating systems. Suse 12/15, Oracle Linux 6/7/8, Redhat 6/7/8 and a few others.
We've been using Active Directory authentication for some time.
For ...
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How do I clear the dns cache on centos7 and centos8?
I am working on scripting a way to flush dns cache on different linux distros. I want to support doing this with Ubuntu-server, Ubuntu-desktop, Centos8-desktop, and Centos7-server(nogui)
I have built ...
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cache smb mount on local hard drive
I have a smb mount on my linux server, but occasionally it loses connection, interrupting the software using the mounted directory. Is there a way to cache the smb mount on local disk?
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How to cache downloads to RAM?
This is my first time posting on this forum, I apologise in advance if I inadvertently make any mistakes and welcome any suggestions for question improvements. I am running Ubuntu 22.04.1 on a laptop ...
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bash: adding/removing duplicate programs executes the wrong ones [duplicate]
i'm currently testing the install target (which installs into /usr/local/bin) of some software (that is also installed via my package manager into /usr/bin), and noticed that bash doesn't find the ...
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NUMA aware caching on linux
This is a follow-up question to dentry/inode caching on multi-cpu machines / memory allocator configuration, but here I try to put the question differently.
My problem is that I have a dual socket ...
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dentry/inode caching on multi-cpu machines / memory allocator configuration
While doing performance benchmarking on CPLEX, I ran across a strange issue. The details are posted in a blog: https://community.ibm.com/community/user/ai-datascience/blogs/xavier-nodet1/2021/07/08/...
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Unable to use perf to find L3 Cache miss rate
I am trying to get the L3 cache miss rate when I try to use perf. The following is the command I run:
perf stat -e instructions,LLC-load-misses,LLC-loads ./program <arg1> <arg2> <arg3&...
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DDR memory errors or page cache corruption?
System: embedded, arm64 (4xCortexA53), 2GB LPDDR3, eMMC memory, Linux, kernel 5.4.17.
I am experiencing issues with random system crash, that in normal operation will happen every 2 days to every &...
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Does cygserver improve Cygwin performance? If so, with what tasks?
I've read that cygserver can improve performance in some circumstances but I'm not really clear on how - or on how to know whether it's applicable to our use case.
Can anyone provide any insights?
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Clean ways to prime the kernel inode cache after boot?
Various answers on various StackExchange sites cover parts of this topic, but I did not see an exact match for this scenario. How can you identify every mounted standard filesystem, and traverse all ...
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linux drop_cache using "echo 3 > /proc/sys/vm/drop_caches" not working as expected
In our production environment we are running drop cache command echo 3 > /proc/sys/vm/drop_caches to free the RAM. But also what I found is dropping caches is not a good practice and also it won't ...
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Is rsync really a culprit for causing low memory on our VM?
In a VM of 16GB RAM, we are running rsync as a cron job(for every 10 minutes) on our production to sync GBs of folder from AWS EFS to local storage. After few days of running we found that the VM is ...
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Is file cache flushed automatically after time?
Let's say I copy a file using cp and the proccess returns immedietly because the file was written to cache.
Then I leave the PC alone for 1 hour. Nothing special running on it.
Is the cache flushed ...
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Does logging into a shell session build a cache of executables on the path which never gets updated? [duplicate]
I notice that when I compile a custom build of a packaged program stored in /usr/bin eg /usr/bin/emacs, which emacs shows the already existing executable at /usr/bin/emacs instead /usr/local/bin/emacs,...
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How to properly set buff/cache consumption. Linux starts to swap memory, even that there is a lot lot "available" memory?
I have following free -h output
total: 125g
used: 54g
free: 1g
shared: 1,3g
buff/cache/: 70g
available: 67g
swap total: 151
swap used: 10gb
cat /proc/meminfo
buffers: 274496kb
cached: ...
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Is it possible to load up a binary into ram, without executing it?
Like I will use google chrome whenever I use linux (most probably) But I don't want it to auto start when ever I open it. I could open it manually, but I have HDD so it is pain to load for the first ...
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Search [not install] without syncthing on Fedora
I would want to know if it is possible to search packages in Fedora (using dnf) without it having to sync anything previously.
I've read Fedora wiki about rpm, but I don't think I understand properly ...
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Is it safe to clear the buffers and cache on a linux server
After reading this link: How do you empty the buffers and cache on a Linux system?, I know that there are some commands that can help us to empty the buffers and cache of the OS.
But I'm not sure if ...
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How to change the default BDI `max_ratio` and/or `min_ratio` for all devices?
I'm using a system with multiple storage devices with different write throughput. As explained in question Why were "USB-stick stall" problems reported in 2013? Why wasn't this problem ...
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Flushing the filesystem cache with a frozen filesystem
I was under the impression that dropping the cache via the vm.drop_caches sysctl would drop all caches, but when I freeze a filesystem and drop the page cache, I can still read the directory:
# fgrep '...
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Why is my system using swap when RAM fills up with cache?
I'm running openSUSE TW, 32 GiB RAM, 64 GiB swap (SSD).
Swap usage is zero up until the point when RAM gets fully filled up with cache.
I'm using htop to monitor it. Yellow/orange = cache
My system ...
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What exactly is being cached when opening/querying a SQLite database
I was asked to improve existing code to query SQLite databases. The original code made a lot of separate calls to the database and filtered the results in Python. Instead, I opted to re-write the ...
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USB drive error SCSI cache
just recognized an unknown error, as i checked my actual log with journalctl -f.
When i unmounted my Backup-USB-disk with unmount /path/to/disk and then pulled the cable out, a short noise occured ...
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Linux Cache cannot be cleared completely, it fills the entire RAM after some days
I use a laptop for work and therefore I only do a suspend to RAM rather than shutdown everyday. so I do not have to start each application again every day.
after some days of "run time" I ...
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How to flush routing cache in Linux?
There is an Oracle Linux 7 system with Unbreakable kernel 5.4.17-2136.304.4.1.el7uek.x86_64 (which is very recent for the RHEL7-like system, which usually uses 3.10-based kernel).
Network interfaces ...
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Do linux processes actually separate cache?
It seems like every time someone complains about how a lot of memory is being used, all of the responses claim that it is just cache, it isn't harmful, it will be reallocated when needed, etc, even ...
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what is the different between Buffer Cache that displayed from free command VS the available memory [closed]
we have 463 RHEL 7.6 machines in the cluster most of then are HDFS machines ( datanode )
from free -g command we can that usually buff/cache is around 30-50 when total memory is 256G
as I know - a ...
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Using excess video memory for disk caching?
On newer Ryzen 5000-based laptops, the integrated graphics controller always gets at least 1GB of shared video memory. In the BIOS settings, 1GB is the minimum. For people who don't need 1GB for video ...
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Disabling any and all forms of write buffering and write caching
I have recently discovered that the cause of my systems' instability is that Linux is buffering writes, and it is doing so for all devices of any form, and it is not caring how much destruction it is ...
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Security concerns for gpg-agent caching the passphrase?
https://www.gnu.org/software/emacs/manual/html_node/pgg/Caching-passphrase.html
When using GnuPG (gpg) as the PGP scheme, we recommend using a program called gpg-agent for entering and caching ...
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How to set GPG cache ttl in a shell script?
How to set gpg-agent --no-allow-external-cache --default-cache-ttl 10 --max-cache-ttl 20 in a shell script? After I issue the command, it gives gpg-agent[4869]: gpg-agent running and available but ...
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How to get cache used per process on *nix systems
I would like to know, what is cache usage per process. Is there a way to do it? I'm currently on Ubuntu.
The problem is, that my PC fills up whole cache, and then when I need RAM just starts swapping ...
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How do I undo copying a file that is ended up in cache?
I have copied a large file to USB drive.
The file appeared to be copied almost instantly, but copying operation stalled at the very end. /proc/meminfo is showing large, gigabyte Dirty: entry which is ...
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Explanation about free, available and buff/cache and how to find what process is buff/cache saved for in a server in the command "free -mh "
I see explanation for free -mh as:
free displays the total amount of free and used physical and swap
memory in the system, as well as the buffers and caches used by
the kernel. The information is ...
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Remove temporary files in chrome, without losing access to websites
My chrome (PortableApps) profile takes above 1Gb.
I found no way of cleaning the cache (to the point of freeing a large fraction of the space taken), without losing access to websites, e.g.
Is that ...
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how to sudoers drop_caches w/o proxy script?
not echo 3 |sudo -k tee /proc/sys/vm/drop_caches as we cant ensure if it will be "3" the value passed.
So, from where could I grantedly get the "3" text and how to write it at ...
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Is it reasonable to have a network-mounted home dir but a local ~/.cache?
I want to free up some space in my network-mounted home directory. I'm noticing that my .cache directory is very big. I was wondering whether I should replace it with a symlink, ~/.cache -> /...
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Is there a way to restrict use of swap to cases when otherwise the OOM-Killer would kick in? [duplicate]
Is there a way to completely restrict using swap if there are buffers/cache in use? And use swap only to prevent Out-Of-Memory Killer.
Is there a way to forbid using swap if are there still buffers/...
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Is it possible to avoid cached data duplication in bcache and Btrfs RAID1?
There is a possibility to attach single bcache cache drive to multiple backing devices. Since bcache is not aware about filesystem which lies on top, this means it is not aware about any software RAID ...
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