On Thu, May 10, 2012 at 04:48:10PM +0200, Michal Privoznik wrote: > On 03.05.2012 10:01, Daniel P. Berrange wrote: > > On Wed, May 02, 2012 at 01:52:27PM -0600, Eric Blake wrote: > >> On 04/27/2012 07:22 AM, Michal Privoznik wrote: > >>> Currently, we are allocating buffer for RPC messages statically. > >>> This is not such pain when RPC limits are small. However, if we want > >>> ever to increase those limits, we need to allocate buffer dynamically, > >>> based on RPC message len (= the first 4 bytes). Therefore we will > >>> decrease our mem usage in most cases and still be flexible enough in > >>> corner cases. > >>> --- > >>> src/rpc/virnetclient.c | 16 ++- > >>> src/rpc/virnetmessage.c | 12 ++- > >>> src/rpc/virnetmessage.h | 6 +- > >>> src/rpc/virnetserverclient.c | 20 ++- > >>> tests/virnetmessagetest.c | 393 +++++++++++++++++++++++------------------- > >>> 5 files changed, 264 insertions(+), 183 deletions(-) > >> > >> I haven't looked closely at this, but I do have a generic question: > >> > >> Are you malloc'ing and free'ing the buffer for each rpc on every call, > >> or are you tracking a pool of buffers and only alloc'ing when needed? > >> Furthermore, can you use the stack or a statically allocated array to > >> receive short messages, saving alloc only for the long messages? I'm > >> worried about performance if we malloc on every single RPC call. > > > > To be honest I'm not convinced malloc() would be a big factor in the > > speed of the RPC calls. That said you could optimize it using the > > VIR_ALLOC_VAR to allocate the virNetMessage struct + the buffer > > in one go. ALlocate all messages with 256kb initially and then you > > can relloc larger only if needed, and re-alloc back to 256 kb when > > done. > > > > > > Daniel > > Okay, point taken. Although I'd rather avoid allocating virNetMessage > struct and buffer at once. It would complicate the code again, because > the client side code has this struct _virNetClient; which already > contains virNetMessage. However, if I'd need to re-alloc, I'd need to > realloc whole message (!) therefore change the member to > virNetMessagePtr. This implies too many changes. Lets just go with your current code for now. We can easily revisit if it proves to be a performance problem later. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list