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6
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1answer
60 views

File backed, locked shared memory and disk interaction

Varnish, a HTTP accelerator, uses a ~80MB file backed SHM log that is mlock()ed into memory. The Varnish docs recommend to store the file on tmpfs to avoid unnecessary disk access. However if the ...
3
votes
1answer
34 views

Grsecurity subject mode x

I am conducting some research on Grsecurity on Hardened Gentoo, see http://en.wikibooks.org/wiki/Grsecurity. To be more specific, I am trying to find an example where subject mode x makes a ...
1
vote
1answer
128 views

proc/sys/vm/flush_mmap_pages missing in 3.9 kernel, how to get it?

There was an option in redHat 5.2 called flush_mmap_pages, I could set this to zero and that would turn of writing dirty pages from a mapped memory file (so I can do it myself when I want to). However ...
1
vote
1answer
427 views

Ext4 exhibits unexpected write latency variance vs. ext2

I have a latency sensitive application running on an embedded system, and I'm seeing some discrepancy between writing to a ext4 partition and an ext2 partition on the same physical device. ...
1
vote
0answers
252 views

Problems when using the framebuffer device directly

I am writing a program using the framebuffer device directly and I have three problems there. 1) The only way I can set the screen resolution correct is by passing the kernel option during boot: ...
4
votes
1answer
671 views

Behavior of mmap'd memory on memory pressure

I have a large tar file (60GB) containing image files. I'm using mmap() on this entire file to read in these images, which are accessed randomly. I'm using mmap() for the following reasons: Thread ...
5
votes
1answer
2k views

Hung system call

So I'm working with a custom kernel module that I'm writing a python front end for. The kernel module works, and it adds a framebuffer device file to /dev/fb1. I can read and write to it fine. I've ...
8
votes
3answers
521 views

Memory size for kernel mmap operation

I'm interested in the way Linux mmaps files into the main memory (in my context its for executing, but I guess the mmap process is the same for writing and reading as well) and which size it uses. So ...