33f611cf7d
Since commit
6be3b0db6d ("xfrm: policy: add inexact policy search tree infrastructure")
policy lookup no longer walks a list but has a set of candidate lists.
This set has to be searched for the best match.
In case there are several matches, the priority wins.
If the priority is also the same, then the historic behaviour with
a single list was to return the first match (first-in-list).
With introduction of serval lists, this doesn't work and a new
'pos' member was added that reflects the xfrm_policy structs position
in the list.
This value is not exported to userspace and it does not need to be
the 'position in the list', it just needs to make sure that
a->pos < b->pos means that a was added to the lists more recently
than b.
This re-walk is expensive when many inexact policies are in use.
Speed this up: when appending the policy to the end of the walker list,
then just take the ->pos value of the last entry made and add 1.
Add a slowpath version to prevent overflow, if we'd assign UINT_MAX
then iterate the entire list and fix the ordering.
While this speeds up insertion considerably finding the insertion spot
in the inexact list still requires a partial list walk.
This is addressed in followup patches.
Before:
./xfrm_policy_add_speed.sh
Inserted 1000 policies in 72 ms
Inserted 10000 policies in 1540 ms
Inserted 100000 policies in 334780 ms
After:
Inserted 1000 policies in 68 ms
Inserted 10000 policies in 1137 ms
Inserted 100000 policies in 157307 ms
Reported-by: Noel Kuntze <noel@familie-kuntze.de>
Cc: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.