Questions tagged [buffer]

This tag is for questions about kernel buffer caches, including pipe buffers. These are used to store the recently accessed files and/or frequently accessed files.

32 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
4
votes
0answers
80 views

Tailing file using less +F/shift-F, turn off line buffering?

When using tail -f, it prints each character as it is written to the file, but less +F won't print until it sees a linefeed. And if the data being written to the file does not contain linefeeds, must ...
4
votes
0answers
695 views

Understanding inotifywait, pipes and buffers

I want to monitor every file change in a directory with inotifywait. inotifywait shall write to a FIFO buffer, which then can be read, leisurely. While experimenting with relatively huge amounts of ...
4
votes
1answer
151 views

Disable buffering in a VM configuration

I am executing some benchmark using a DBMS and virtual machines. And I am using this command free && sync && echo 3 > /proc/sys/vm/drop_caches && free on each Guest, and ...
3
votes
0answers
130 views

Anyone know where to change this “bufsize” value? ( st / mt LTO tape drives )

I am trying to speed test some new LTO tape drives but cannot seem to send data to the tape via dd for any block size above 327,680 bytes. I must have a 1M blocksize for my application. [root@host]# ...
3
votes
0answers
290 views

Does Linux perform buffering twice when hosting a VM?

I ran a KVM VM on my CentOS host and found that after performing a HDD-intensive operation, it used all of the host's memory I assigned to it. However, free on the guest suggests that the memory's ...
3
votes
1answer
274 views

Artificially prime buffer cache?

Is it beneficial to artificially prime the buffer cache when dealing with larger files? Here's a scenario: A large file needs to be processed, line by line. Conceptually, it is easy to parallelize ...
3
votes
0answers
141 views

xdelta3 fails to decode on block device

I'm trying to use xdelta3 to bring a remote block device into sync with a local one. I'm able to easily generate a xdelta3 patch file using the command: xdelta3 -e -B 33554432 -v -9 -I 0 -s /dev/...
2
votes
0answers
78 views

fq_codel not working on saturated link?

I'm setting up a test to saturate a link between two machines with a gig router in between them, then run fq_codel on Debian Buster and see if my ping times can improve (what I think fq_codel is ...
2
votes
0answers
96 views

linux: Discard dirty pages for block device (on usb disconnect)

When forcefully removing a USB device on linux while there are outstanding writes to the device the kernel log fills up with blk_update_request: I/O error, dev sdg, sector 50618368 Buffer I/O error ...
1
vote
1answer
38 views

avoid bash buffering problem in log processing

I have bash buffering a problem similar to what can be found here: Turn off buffering in pipe The socat solution in the above question is quite interesting as I have access to this command in my ...
1
vote
0answers
21 views

Why doesn't sync guarantee that buffers are flushed?

As far as I can see, the only use of sync is to ensure that there's no incomplete information, which is supposed to be safely written on disk but may actually be still only in a volatile buffer. ...
1
vote
0answers
58 views

Unbuffer converting all characters to bell?

When I pipe a large-ish output through unbuffer, all I end up getting is an endless stream of the bell character (u0007). See here, a 1631-character string of arbitrary content piped through unbuffer ...
1
vote
0answers
86 views

hard disk high temperature and frequent access while idle

I have bought two WD Gold 4TB and installed debian sid with kde on a single RAID1 partition, md0: # cat /proc/mdstat Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [...
1
vote
0answers
218 views

Ubuntu crashes on startup with a call trace (release_bts_buffer)

A friend of mine is having problems with her Ubuntu laptop and I have trouble finding informations that could help me know what is going on. I think this is a bit beyond the scope of my abilities. ...
1
vote
0answers
634 views

How does Linux kernel know when to use memory buffer/cache?

When we do a find in linux, I am guessing the kernel will store the result into buffer/cache. Let say after an hour, some changes of the folder and files happened, so my question is, when we do the ...
1
vote
1answer
508 views

Avoiding Buffering With Output Redirection

I'm trying to write some functions I can utilize in my scripts to essentially tag all output as Error vs Standard output, throw date/time stamps on it, and also include the name of the function that ...
0
votes
0answers
48 views

background process with “&” and problem with buffering

I've written this script in the ~/.bashrc file and I've sourced the file, but it's not working properly. It's purpose is to open the link provided by the jupyter notebook in the Chrome browser in a ...
0
votes
0answers
32 views

Displaying a changing buffer in realtime in linux

Sometimes when I am searching for a song on my machine, I use the following: locate *artist*.mp3 | sort | less The thing about this is that the sort will buffer until all files have been located, ...
0
votes
0answers
60 views

PuTTY (or other terminal) with output buffering for slow connection

I'm looking for terminal that can buffer output (keystrokes) before sending them. I need this, because I have some devices on very slow and not reliable connections (ping 400-600ms, 20% packet loss) ...
0
votes
0answers
19 views

Linux RedHat write buffer config

I have Linux RedHat 6.2. How do I configure files to buffer 4096 (or higher 2^N values) bytes before writes? Of course, when an EOF is received, write the file.
0
votes
0answers
407 views

UDP send buffer error in netstat

I we are running voice application which stream UDP (RTP) packets for voice, I am investigation some strange issue where my ifconfig ens4 | grep error counter going up specifically overrun If you see ...
0
votes
0answers
617 views

flush tty device buffer from terminal

I have a serial device on /dev/ttyAMA0. I have program written in C that communicates with this device. But apart from the C program I sometimes need to input some configuration data from terminal, ...
0
votes
0answers
35 views

Sizing of Samba Linux Server

Do you know any performance of sizing recommendations about Samba 4.7.1 ? For few informations : 2vCPUs / 1 Core 8GB of RAM 140 simultaneous Windows users / 250 at most / 20 NFS volumes mounted via ...
0
votes
0answers
36 views

Finding usage of “buff/cache” (as mentioned in free)?

When I run free, I see free -h total used free shared buff/cache available Mem: 15Gi 1.7Gi 4.3Gi 149Mi 9.5Gi ...
0
votes
0answers
92 views

Buffering issue when looking at netcat output

I have problem I am trying to understand: I am sending some UDP data to local host. It is a simple UDP packet with a counter. It counts up to 16 (0xF) and stops. When I grep the received data on the ...
0
votes
0answers
45 views

How to get the network buffer usage of some process

I have an Ubuntu server, which contains some user-processes. It always crashes after starting-up several hours. "crashes" means that I cannot neither ssh to it nor ping it anymore. I'm doubting that ...
0
votes
2answers
494 views

Is a buffer always on the hash queue?

The author while talking about buffer cache in the book - The design of the UNIX operating system, says that a buffer is always on a hash queue, but it may or may not be on the free list. What ...
0
votes
1answer
231 views

Wanted: nonassociative array in AWK

I am looking at speeding up some code in AWK by serially processing an internal string representation instead of serially processing an array representation. (For Examples 1 and 2 below assume ...
0
votes
0answers
116 views

Backup server with tar, encrypt and directly transfer the result, AFTER BUFFERING IT

So I've been investigative how to make full backups with tar, and I found that tar is a good tool if the backup is to be made once, and if the server has enough disk space to handle the output file. ...
0
votes
1answer
88 views

:bnext not cycling through all buffers in vim

For some reason :bnext is not cycling though all the buffers shown by :buffers I have 5 buffers open but only 3 buffers are visited when I used :bnext repeatedly. How can I cycle through all the ...
0
votes
1answer
540 views

Preventing a new instance of a program to open when calling it

My problem is with FBI (frame buffer image viewer) for Linux, but my question and any answers are perhaps applicable to more than only that program. I don't know. Anyway… While things are loading on ...
0
votes
1answer
75 views

Linux FIFO buffering depends on invocation order of readers and writers

I'm trying to write a simple python script that reads from a fifo and then writes to another fifo. I have created two FIFOs using the following command: $ mkfifo input $ mkfifo output I invoke the ...