Re: [PATCH iproute2-next] tc: use ll_init_map() only when needed

Jamal Hadi Salim
2026-04-30T18:20:23Z

On Thu, Apr 30, 2026 at 11:36 AM David Ahern <dsahern@kernel.org> wrote:
>
> Jamal: waiting for your review ...
>
> On 4/28/26 2:28 AM, Eric Dumazet wrote:
> > Some setups can have thousands of devices.
> >
> > ll_init_map() is rather expensive for them.
> >
> > Only call ll_init_map() in the following cases:
> >
> > 1) tc runs in batch mode.
> > 2) tc runs in monitor mode.
> > 3) tc dumps qdiscs/classes/filters for all netdev.
> >
> > This greatly reduces RTNL pressure on common operations.
> >
> > Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>

cheers,
jamal

> > ---
> > tc/f_route.c | 1 -
> > tc/m_mirred.c | 2 --
> > tc/tc.c | 1 +
> > tc/tc_class.c | 6 ++----
> > tc/tc_filter.c | 32 ++++++++++++++++----------------
> > tc/tc_qdisc.c | 5 ++---
> > 6 files changed, 21 insertions(+), 26 deletions(-)
> >
> > diff --git a/tc/f_route.c b/tc/f_route.c
> > index 96b99b06be179c90dfb0d24d9577b5206dd98ef1..c234ddf0cb9309556844c85047d0f9ef53a2fd7b 100644
> > --- a/tc/f_route.c
> > +++ b/tc/f_route.c
> > @@ -76,7 +76,6 @@ static int route_parse_opt(const struct filter_util *qu, char *handle, int argc,
> > __u32 id;
> >
> > NEXT_ARG();
> > - ll_init_map(&rth);
> > if ((id = ll_name_to_index(*argv)) <= 0) {
> > fprintf(stderr, "Illegal \"fromif\"\n");
> > return -1;
> > diff --git a/tc/m_mirred.c b/tc/m_mirred.c
> > index f4da3c76284460d7f4bb73c7c3c172732f054632..e9ae5199432e828026f15ce226c5f5f84998c660 100644
> > --- a/tc/m_mirred.c
> > +++ b/tc/m_mirred.c
> > @@ -213,8 +213,6 @@ parse_direction(const struct action_util *a, int *argc_p, char ***argv_p,
> > if (d[0]) {
> > int idx;
> >
> > - ll_init_map(&rth);
> > -
> > idx = ll_name_to_index(d);
> > if (!idx)
> > return nodev(d);
> > diff --git a/tc/tc.c b/tc/tc.c
> > index 0fc658c881f0f553f1f1f8d87b46943d4d0eed8f..7d69e4d533a98b9c071cb954443a049a52252f2c 100644
> > --- a/tc/tc.c
> > +++ b/tc/tc.c
> > @@ -243,6 +243,7 @@ static int batch(const char *name)
> > return -1;
> > }
> >
> > + ll_init_map(&rth);
> > ret = do_batch(name, force, tc_batch_cmd, NULL);
> >
> > rtnl_close(&rth);
> > diff --git a/tc/tc_class.c b/tc/tc_class.c
> > index 6d707d8c924f4b5e90201d4de8e9779f82ce17f3..9aace019e6c8b96fb51edb4fe89bea5b7469beed 100644
> > --- a/tc/tc_class.c
> > +++ b/tc/tc_class.c
> > @@ -136,11 +136,11 @@ static int tc_class_modify(int cmd, unsigned int flags, int argc, char **argv)
> > }
> >
> > if (d[0]) {
> > - ll_init_map(&rth);
> > -
> > req.t.tcm_ifindex = ll_name_to_index(d);
> > if (!req.t.tcm_ifindex)
> > return -nodev(d);
> > + } else {
> > + ll_init_map(&rth);
> > }
> >
> > if (rtnl_talk(&rth, &req.n, NULL) < 0)
> > @@ -437,8 +437,6 @@ static int tc_class_list(int argc, char **argv)
> > argc--; argv++;
> > }
> >
> > - ll_init_map(&rth);
> > -
> > if (d[0]) {
> > t.tcm_ifindex = ll_name_to_index(d);
> > if (!t.tcm_ifindex)
> > diff --git a/tc/tc_filter.c b/tc/tc_filter.c
> > index 7db850bda11a3408ec66b457c9fc590f3a734f65..be70e360849e5058192640da0f061810a99e2ea8 100644
> > --- a/tc/tc_filter.c
> > +++ b/tc/tc_filter.c
> > @@ -188,16 +188,17 @@ static int tc_filter_modify(int cmd, unsigned int flags, int argc, char **argv)
> > addattr_l(&req.n, sizeof(req), TCA_KIND, k, strlen(k)+1);
> >
> > if (d[0]) {
> > - ll_init_map(&rth);
> > -
> > req.t.tcm_ifindex = ll_name_to_index(d);
> > if (req.t.tcm_ifindex == 0) {
> > fprintf(stderr, "Cannot find device \"%s\"\n", d);
> > return 1;
> > }
> > - } else if (block_index) {
> > - req.t.tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
> > - req.t.tcm_block_index = block_index;
> > + } else {
> > + ll_init_map(&rth);
> > + if (block_index) {
> > + req.t.tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
> > + req.t.tcm_block_index = block_index;
> > + }
> > }
> >
> > if (q) {
> > @@ -539,8 +540,6 @@ static int tc_filter_get(int cmd, unsigned int flags, int argc, char **argv)
> > }
> >
> > if (d[0]) {
> > - ll_init_map(&rth);
> > -
> > req.t.tcm_ifindex = ll_name_to_index(d);
> > if (!req.t.tcm_ifindex)
> > return -nodev(d);
> > @@ -704,21 +703,22 @@ static int tc_filter_list(int cmd, int argc, char **argv)
> >
> > req.t.tcm_info = TC_H_MAKE(prio<<16, protocol);
> >
> > - ll_init_map(&rth);
> > -
> > if (d[0]) {
> > req.t.tcm_ifindex = ll_name_to_index(d);
> > if (!req.t.tcm_ifindex)
> > return -nodev(d);
> > filter_ifindex = req.t.tcm_ifindex;
> > - } else if (block_index) {
> > - if (!tc_qdisc_block_exists(block_index)) {
> > - fprintf(stderr, "Cannot find block \"%u\"\n", block_index);
> > - return 1;
> > + } else {
> > + ll_init_map(&rth);
> > + if (block_index) {
> > + if (!tc_qdisc_block_exists(block_index)) {
> > + fprintf(stderr, "Cannot find block \"%u\"\n", block_index);
> > + return 1;
> > + }
> > + req.t.tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
> > + req.t.tcm_block_index = block_index;
> > + filter_block_index = block_index;
> > }
> > - req.t.tcm_ifindex = TCM_IFINDEX_MAGIC_BLOCK;
> > - req.t.tcm_block_index = block_index;
> > - filter_block_index = block_index;
> > }
> >
> > if (filter_chain_index_set)
> > diff --git a/tc/tc_qdisc.c b/tc/tc_qdisc.c
> > index 7eb9a31baa31fb91a8141c9eca1135e76a52fa8b..252ea861f249a5a71cf782389776e68c3e48c6cc 100644
> > --- a/tc/tc_qdisc.c
> > +++ b/tc/tc_qdisc.c
> > @@ -193,8 +193,6 @@ static int tc_qdisc_modify(int cmd, unsigned int flags, int argc, char **argv)
> > if (d[0]) {
> > int idx;
> >
> > - ll_init_map(&rth);
> > -
> > idx = ll_name_to_index(d);
> > if (!idx)
> > return -nodev(d);
> > @@ -411,13 +409,14 @@ static int tc_qdisc_list(int argc, char **argv)
> > argc--; argv++;
> > }
> >
> > - ll_init_map(&rth);
> >
> > if (d[0]) {
> > req.t.tcm_ifindex = ll_name_to_index(d);
> > if (!req.t.tcm_ifindex)
> > return -nodev(d);
> > filter_ifindex = req.t.tcm_ifindex;
> > + } else {
> > + ll_init_map(&rth);
> > }
> >
> > if (dump_invisible) {
>