* si_swapinfo export @ 2011-09-02 15:41 George Shuklin 2011-09-02 16:18 ` Christoph Lameter 2011-09-02 19:53 ` Valdis.Kletnieks 0 siblings, 2 replies; 4+ messages in thread From: George Shuklin @ 2011-09-02 15:41 UTC (permalink / raw) To: linux-kernel Good day. Why si_swapinfo (from include/linux/swap.h) is not marked as EXPORT_SYMBOL_GPL? It's kinda hard to gain information about memory in module. /proc/meminfo Contain more information than module can gain without special tricks... Thanks. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: si_swapinfo export 2011-09-02 15:41 si_swapinfo export George Shuklin @ 2011-09-02 16:18 ` Christoph Lameter 2011-09-02 19:53 ` Valdis.Kletnieks 1 sibling, 0 replies; 4+ messages in thread From: Christoph Lameter @ 2011-09-02 16:18 UTC (permalink / raw) To: George Shuklin; +Cc: linux-kernel On Fri, 2 Sep 2011, George Shuklin wrote: > Why si_swapinfo (from include/linux/swap.h) is not marked as > EXPORT_SYMBOL_GPL? It's kinda hard to gain information about memory in > module. No one needed it from a module so far. Submit your code with a patch that exports si_swapinfo if you need it. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: si_swapinfo export 2011-09-02 15:41 si_swapinfo export George Shuklin 2011-09-02 16:18 ` Christoph Lameter @ 2011-09-02 19:53 ` Valdis.Kletnieks 2011-09-03 0:52 ` George Shuklin 1 sibling, 1 reply; 4+ messages in thread From: Valdis.Kletnieks @ 2011-09-02 19:53 UTC (permalink / raw) To: George Shuklin; +Cc: linux-kernel [-- Attachment #1: Type: text/plain, Size: 460 bytes --] On Fri, 02 Sep 2011 19:41:29 +0400, George Shuklin said: > Good day. > > Why si_swapinfo (from include/linux/swap.h) is not marked as > EXPORT_SYMBOL_GPL? It's kinda hard to gain information about memory in > module. Use case? What information exactly are you trying to get in the module, and equally important, why? More likely, what you *actually* want isn't the information, it's a new API (or using an existing one you didn't even know was there) :) [-- Attachment #2: Type: application/pgp-signature, Size: 227 bytes --] ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: si_swapinfo export 2011-09-02 19:53 ` Valdis.Kletnieks @ 2011-09-03 0:52 ` George Shuklin 0 siblings, 0 replies; 4+ messages in thread From: George Shuklin @ 2011-09-03 0:52 UTC (permalink / raw) To: Valdis.Kletnieks; +Cc: linux-kernel Well, in my personal case it is some 'memory pressure service' for virtual machines in xen environment. It check about 1-2 times per second memory state and report it to management software outside VM. Right now this is userspace program, which reads /proc/meminfo and sends it via xenstore (interdomain communication system) to management domain. It works fine, but we need to do double int-str conversion (/proc/meminfo do itoa, our daemon sens this to control domain, daemon in control domain do atoi and math to get right memory value). This is very inefficient, especially when we talks about bunch of VM per host. kernel module can do math internally with ints, not with strings (no conversion at all) - this will save pretty much time (my calculation is about one-two of CPU time per day for every virtualization host with about 50-100 active VMs. The information I needs is amount of 'really free' memory. We calculate it as (roughly) as MemFree+Buffers+Cached+(SwapTotal-SwapFree), and our management system trying to keep this value within expected values (f.e. within interval 128-256Mb). This allows us to prevent VM's swapping and allow VM to push to swap really rare used pages (and their place actually used for caching). On 02.09.2011 23:53, Valdis.Kletnieks@vt.edu wrote: > On Fri, 02 Sep 2011 19:41:29 +0400, George Shuklin said: >> Good day. >> >> Why si_swapinfo (from include/linux/swap.h) is not marked as >> EXPORT_SYMBOL_GPL? It's kinda hard to gain information about memory in >> module. > Use case? What information exactly are you trying to get in the module, and > equally important, why? More likely, what you *actually* want isn't the > information, it's a new API (or using an existing one you didn't even know was > there) :) > ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2011-09-03 0:51 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-09-02 15:41 si_swapinfo export George Shuklin 2011-09-02 16:18 ` Christoph Lameter 2011-09-02 19:53 ` Valdis.Kletnieks 2011-09-03 0:52 ` George Shuklin
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