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[iproute2-next,0/2] Add copy-on-fork to get sys command

Message ID 20210428114231.96944-1-galpress@amazon.com
Headers show
Series Add copy-on-fork to get sys command | expand

Message

Gal Pressman April 28, 2021, 11:42 a.m. UTC 
This is the userspace part for the new copy-on-fork attribute added to
the get sys netlink command.

The new attribute indicates that the kernel copies DMA pages on fork,
hence fork support through madvise and MADV_DONTFORK is not needed.

Kernel series was merged:
https://lore.kernel.org/linux-rdma/20210418121025.66849-1-galpress@amazon.com/

Thanks

Gal Pressman (2):
  rdma: update uapi headers
  rdma: Add copy-on-fork to get sys command

 rdma/include/uapi/rdma/rdma_netlink.h | 16 ++++++++++++++++
 rdma/sys.c                            |  9 +++++++++
 2 files changed, 25 insertions(+)

Comments

Gal Pressman April 29, 2021, 6:40 a.m. UTC | #1 
On 28/04/2021 15:00, Leon Romanovsky wrote:
> On Wed, Apr 28, 2021 at 02:42:31PM +0300, Gal Pressman wrote:

>> The new attribute indicates that the kernel copies DMA pages on fork,

>> hence fork support through madvise and MADV_DONTFORK is not needed.

>>

>> If the attribute is not reported (expected on older kernels),

>> copy-on-fork is disabled.

>>

>> Example:

>> $ rdma sys

>> netns shared

>> copy-on-fork on

> 

> I don't think that we need to print them on separate lines.

> $ rdma sys

> netns shared copy-on-fork on


Ack.

>> Signed-off-by: Gal Pressman <galpress@amazon.com>

>> ---

>>  rdma/sys.c | 9 +++++++++

>>  1 file changed, 9 insertions(+)

>>

>> diff --git a/rdma/sys.c b/rdma/sys.c

>> index 8fb565d70598..dd9c6da33e2a 100644

>> --- a/rdma/sys.c

>> +++ b/rdma/sys.c

>> @@ -38,6 +38,15 @@ static int sys_show_parse_cb(const struct nlmsghdr *nlh, void *data)

>>  		print_color_string(PRINT_ANY, COLOR_NONE, "netns", "netns %s\n",

>>  				   mode_str);

>>  	}

>> +

>> +	if (tb[RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK])

>> +		print_color_on_off(PRINT_ANY, COLOR_NONE, "copy-on-fork",

>> +				   "copy-on-fork %s\n",

>> +				   mnl_attr_get_u8(tb[RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK]));

>> +	else

>> +		print_color_on_off(PRINT_ANY, COLOR_NONE, "copy-on-fork",

>> +				   "copy-on-fork %s\n", false);

> 

> Let's simplify it

>         bool cow = false;

> 

>  +	if (tb[RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK])

>  +		cow = mnl_attr_get_u8(tb[RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK]);

>  +

>  +	print_color_on_off(PRINT_ANY, COLOR_NONE, "copy-on-fork", "copy-on-fork %s", cow);


Ack (changed cow -> cof).

Thanks