Re: [libvirt] [PATCH 9/9] virStream{Recv, Send}All: Increase client buffer

These are wrappers over virStreamRecv and virStreamSend so that users have to care about nothing but writing data into / reading data from a sink (typically a file). Note, that these wrappers are used exclusively on client side as the daemon has slightly different approach. Anyway, the wrappers allocate this buffer and use it for intermediate data storage until the data is passed to stream to send, or to the client application. So far, we are using 64KB buffer. This is enough, but suboptimal because server can send messages up to VIR_NET_MESSAGE_LEGACY_PAYLOAD_MAX bytes big (262120B, roughly 256KB). So if we make the buffer this big, a single message containing the data is sent instead of for,

which is current situation. This means lower overhead, because each message contains a header which needs to be processed, each message is processed roughly same amount of time regardless of its size, less bytes need to be sent through the wire, and so on. Note that since server will never sent us a stream message bigger than VIR_NET_MESSAGE_LEGACY_PAYLOAD_MAX there's no point in sizing up the client buffer past this threshold. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/libvirt-stream.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/libvirt-stream.c b/src/libvirt-stream.c index c16f586..8384b37 100644 --- a/src/libvirt-stream.c +++ b/src/libvirt-stream.c @@ -23,6 +23,7 @@ #include "datatypes.h" #include "viralloc.h" #include "virlog.h" +#include "rpc/virnetprotocol.h" VIR_LOG_INIT("libvirt.stream"); @@ -330,7 +331,7 @@ virStreamSendAll(virStreamPtr stream, void *opaque) { char *bytes = NULL; - int want = 1024*64; + size_t want = VIR_NET_MESSAGE_LEGACY_PAYLOAD_MAX; int ret = -1; VIR_DEBUG("stream=%p, handler=%p, opaque=%p", stream, handler, opaque); @@ -423,7 +424,7 @@ virStreamRecvAll(virStreamPtr stream, void *opaque) { char *bytes = NULL; - int want = 1024*64; + size_t want = VIR_NET_MESSAGE_LEGACY_PAYLOAD_MAX; int ret = -1; VIR_DEBUG("stream=%p, handler=%p, opaque=%p", stream, handler, opaque);