I/O event notification mechanism - select() or epoll() ?
Hi, I have to capture kernel udev events through libudev. One of API provides asynchronous events by reading on file descriptor. I found that there two ways to do that. 1) select call 2) epoll I also found that epoll is smarter and meant to replace old select call. What are your thoughts on these ? Which one is better ? Thanks Rahul B.
On Wed, Sep 26, 2012 at 7:49 PM, Rahul Bedarkar <rpal143@gmail.com> wrote:
Hi,
I have to capture kernel udev events through libudev. One of API provides asynchronous events by reading on file descriptor. I found that there two ways to do that.
1) select call
I guessed when u called select() it will block, and so u can be very efficient - doing nothing until necessary, but also resource being used up - as the process is solely dedicated to listenting for event only.
2) epoll
good thing is u can parallel process other stuff at the same time, if after polling the replies from udev is not back yet. but the bad thing is response may not be so immediate, as u may be doing something else when the udev event comes in.
I also found that epoll is smarter and meant to replace old select call.
What are your thoughts on these ? Which one is better ?
Thanks Rahul B.
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Hi! On 17:19 Wed 26 Sep , Rahul Bedarkar wrote:
Hi,
I have to capture kernel udev events through libudev. One of API provides asynchronous events by reading on file descriptor. I found that there two ways to do that.
1) select call 2) epoll
I also found that epoll is smarter and meant to replace old select call.
What are your thoughts on these ? Which one is better ?
If you are ok to be limited to linux, I would highly recommend using epoll because of scaleability. Using select is almost like creating a new epoll descriptor for every call instead of reusing it. -Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com
Thanks Michi and Peter ! On Fri, Sep 28, 2012 at 10:53 AM, <michi1@michaelblizek.twilightparadox.com> wrote:
Hi!
On 17:19 Wed 26 Sep , Rahul Bedarkar wrote:
Hi,
I have to capture kernel udev events through libudev. One of API provides asynchronous events by reading on file descriptor. I found that there two ways to do that.
1) select call 2) epoll
I also found that epoll is smarter and meant to replace old select call.
What are your thoughts on these ? Which one is better ?
If you are ok to be limited to linux, I would highly recommend using epoll because of scaleability. Using select is almost like creating a new epoll descriptor for every call instead of reusing it.
-Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com
On Wed, Sep 26, 2012 at 05:19:50PM +0530, Rahul Bedarkar wrote:
Hi,
I have to capture kernel udev events through libudev. One of API provides asynchronous events by reading on file descriptor. I found that there two ways to do that.
1) select call 2) epoll
I also found that epoll is smarter and meant to replace old select call.
What are your thoughts on these ? Which one is better ?
I personally prefer event loop libraries such as libev[1]. They handle all the interfacing with the event mechanism the OS provides, so you only need to register a callback function. HTH, Jonathan Neuschäfer [1] http://software.schmorp.de/pkg/libev.html
participants (4)
-
Jonathan Neuschäfer -
michi1＠michaelblizek.twilightparadox.com -
Peter Teoh -
Rahul Bedarkar