RE: [PATCH net-next 01/10] hv_netvsc: Resize some of the variables in hv_netvsc_packet

From: KY Srinivasan
Date: Tue Nov 24 2015 - 11:45:36 EST




> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx]
> Sent: Tuesday, November 24, 2015 12:48 AM
> To: KY Srinivasan <kys@xxxxxxxxxxxxx>
> Cc: davem@xxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; olaf@xxxxxxxxx;
> apw@xxxxxxxxxxxxx; jasowang@xxxxxxxxxx
> Subject: Re: [PATCH net-next 01/10] hv_netvsc: Resize some of the variables
> in hv_netvsc_packet
>
> "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx> writes:
>
> > As part of reducing the size of the hv_netvsc_packet, resize some of the
> > variables based on their usage.
> >
> > Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> > Reviewed-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> > ---
> > drivers/net/hyperv/hyperv_net.h | 14 +++++++-------
> > 1 files changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/hyperv/hyperv_net.h
> b/drivers/net/hyperv/hyperv_net.h
> > index 5fa98f5..972e562 100644
> > --- a/drivers/net/hyperv/hyperv_net.h
> > +++ b/drivers/net/hyperv/hyperv_net.h
> > @@ -127,11 +127,11 @@ struct ndis_tcp_ip_checksum_info;
> > */
> > struct hv_netvsc_packet {
> > /* Bookkeeping stuff */
> > - u32 status;
> > + u8 status;
> >
> > - bool is_data_pkt;
> > - bool xmit_more; /* from skb */
> > - bool cp_partial; /* partial copy into send buffer */
> > + u8 is_data_pkt;
> > + u8 xmit_more; /* from skb */
> > + u8 cp_partial; /* partial copy into send buffer */
>
> These are flags so we can make them bitfields and save even more space.

I am not done with restructuring this structure yet. Once I get this to the bare minimum
I will look at using bitfields.

K. Y
>
> >
> > u16 vlan_tci;
> >
> > @@ -147,13 +147,13 @@ struct hv_netvsc_packet {
> > /* This points to the memory after page_buf */
> > struct rndis_message *rndis_msg;
> >
> > - u32 rmsg_size; /* RNDIS header and PPI size */
> > - u32 rmsg_pgcnt; /* page count of RNDIS header and PPI */
> > + u8 rmsg_size; /* RNDIS header and PPI size */
> > + u8 rmsg_pgcnt; /* page count of RNDIS header and PPI */
> >
> > u32 total_data_buflen;
> > /* Points to the send/receive buffer where the ethernet frame is */
> > void *data;
> > - u32 page_buf_cnt;
> > + u8 page_buf_cnt;
> > struct hv_page_buffer *page_buf;
> > };
>
> --
> Vitaly
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