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Improve batch and dump times by caching link lookups

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ip route uses ll_name_to_index and ll_index_to_name to convert between
device names and indices. At the moment both use for the ioctl based glibc
functions if_nametoindex and if_indextoname and does not cache the result.
When using a batch file or dumping large number of routes this means the
same device lookups can be done repeatedly adding unnecessary overhead
(socket + ioctl + close for each device lookup).

Add a new function, ll_link_get, to send a netlink based RTM_GETLINK. If
successful, cache the result in idx_head and name_head so future lookups
can re-use the entry. Update ll_name_to_index and ll_index_to_name to use
ll_link_get and only fallback to the glibc functions if it fails.

With this change the time to install 720,022 routes with 2 ecmp nexthops
where the nexthop device is given is reduced from 31.4 seconds to 19.2
seconds. A dump of those routes drops from 13.3 to 2.8 seconds.

Signed-off-by: David Ahern <dsahern@gmail.com>
This commit is contained in:
David Ahern 2019-02-13 15:56:30 -08:00
parent db1aafd883
commit 55870dfe7f
1 changed files with 51 additions and 1 deletions
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50
lib/ll_map.c
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@ -152,6 +152,48 @@ static unsigned int ll_idx_a2n(const char *name)
return idx;
}
static int ll_link_get(const char *name, int index)
{
struct {
struct nlmsghdr n;
struct ifinfomsg ifm;
char buf[1024];
} req = {
.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
.n.nlmsg_flags = NLM_F_REQUEST,
.n.nlmsg_type = RTM_GETLINK,
.ifm.ifi_index = index,
};
__u32 filt_mask = RTEXT_FILTER_VF | RTEXT_FILTER_SKIP_STATS;
struct rtnl_handle rth = {};
struct nlmsghdr *answer;
int rc = 0;
if (rtnl_open(&rth, 0) < 0)
return 0;
addattr32(&req.n, sizeof(req), IFLA_EXT_MASK, filt_mask);
if (name)
addattr_l(&req.n, sizeof(req), IFLA_IFNAME, name,
strlen(name) + 1);
if (rtnl_talk(&rth, &req.n, &answer) < 0)
goto out;
/* add entry to cache */
rc = ll_remember_index(answer, NULL);
if (!rc) {
struct ifinfomsg *ifm = NLMSG_DATA(answer);
rc = ifm->ifi_index;
}
free(answer);
out:
rtnl_close(&rth);
return rc;
}
const char *ll_index_to_name(unsigned int idx)
{
static char buf[IFNAMSIZ];
@ -164,6 +206,12 @@ const char *ll_index_to_name(unsigned int idx)
if (im)
return im->name;
if (ll_link_get(NULL, idx) == idx) {
im = ll_get_by_index(idx);
if (im)
return im->name;
}
if (if_indextoname(idx, buf) == NULL)
snprintf(buf, IFNAMSIZ, "if%u", idx);
@ -204,6 +252,8 @@ unsigned ll_name_to_index(const char *name)
if (im)
return im->index;
idx = ll_link_get(name, 0);
if (idx == 0)
idx = if_nametoindex(name);
if (idx == 0)
idx = ll_idx_a2n(name);