> From: Joe Perches [mailto:joe@xxxxxxxxxxx] > Sent: Friday, April 8, 2016 9:15 > On Thu, 2016-04-07 at 18:36 -0700, Dexuan Cui wrote: > > diff --git a/include/net/af_hvsock.h b/include/net/af_hvsock.h > [] > > +#define VMBUS_RINGBUFFER_SIZE_HVSOCK_RECV (5 * PAGE_SIZE) > > +#define VMBUS_RINGBUFFER_SIZE_HVSOCK_SEND (5 * PAGE_SIZE) > > + > > +#define HVSOCK_RCV_BUF_SZ > VMBUS_RINGBUFFER_SIZE_HVSOCK_RECV > > +#define HVSOCK_SND_BUF_SZ PAGE_SIZE > [] > > +struct hvsock_sock { > [] > > + struct { > > + struct vmpipe_proto_header hdr; > > + char buf[HVSOCK_SND_BUF_SZ]; > > + } __packed send; > > + > > + struct { > > + struct vmpipe_proto_header hdr; > > + char buf[HVSOCK_RCV_BUF_SZ]; > > + unsigned int data_len; > > + unsigned int data_offset; > > + } __packed recv; > > +}; > > These bufs are not page aligned and so can span pages. > > Is there any value in allocating these bufs separately > as pages instead of as a kmalloc? The bufs are not required to be page aligned. Here the 'hdr' and the 'buf' must be consecutive, i.e., the 'buf' must be an array rather than a pointer: please see hvsock_send_data(). It looks to me there is no big value to make sure the 'buf' is page aligned: on x86_64, at least it should already be 8-byte aligned due to the adjacent channel pointer, so memcpy_from_msg() should work enough good and in hvsock_send_data() -> vmbus_sendpacket(), we don't copy the 'buf'. Thanks, -- Dexuan _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
