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From: Nathan Chancellor <nathan@kernel.org>
To: Magnus Karlsson <magnus.karlsson@gmail.com>
Cc: magnus.karlsson@intel.com, bjorn@kernel.org, ast@kernel.org,
	daniel@iogearbox.net, netdev@vger.kernel.org,
	maciej.fijalkowski@intel.com, ciara.loftus@intel.com,
	jonathan.lemon@gmail.com, bpf@vger.kernel.org,
	anthony.l.nguyen@intel.com, llvm@lists.linux.dev
Subject: Re: [PATCH bpf-next 06/13] xsk: optimize for aligned case
Date: Tue, 28 Sep 2021 16:15:21 -0700	[thread overview]
Message-ID: <YVOiCYXTL63R4Mu9@archlinux-ax161> (raw)
In-Reply-To: <20210922075613.12186-7-magnus.karlsson@gmail.com>

On Wed, Sep 22, 2021 at 09:56:06AM +0200, Magnus Karlsson wrote:
> From: Magnus Karlsson <magnus.karlsson@intel.com>
> 
> Optimize for the aligned case by precomputing the parameter values of
> the xdp_buff_xsk and xdp_buff structures in the heads array. We can do
> this as the heads array size is equal to the number of chunks in the
> umem for the aligned case. Then every entry in this array will reflect
> a certain chunk/frame and can therefore be prepopulated with the
> correct values and we can drop the use of the free_heads stack. Note
> that it is not possible to allocate more buffers than what has been
> allocated in the aligned case since each chunk can only contain a
> single buffer.
> 
> We can unfortunately not do this in the unaligned case as one chunk
> might contain multiple buffers. In this case, we keep the old scheme
> of populating a heads entry every time it is used and using
> the free_heads stack.
> 
> Also move xp_release() and xp_get_handle() to xsk_buff_pool.h. They
> were for some reason in xsk.c even though they are buffer pool
> operations.
> 
> Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>

My apologies if this has already been reported (I have not seen a report
on netdev nor a report from Intel around it) but this patch as
commit 94033cd8e73b ("xsk: Optimize for aligned case") in -next causes
the following build failure with clang + x86_64 allmodconfig:

net/xdp/xsk_buff_pool.c:465:15: error: variable 'xskb' is uninitialized when used here [-Werror,-Wuninitialized]
                        xp_release(xskb);
                                   ^~~~
net/xdp/xsk_buff_pool.c:455:27: note: initialize the variable 'xskb' to silence this warning
        struct xdp_buff_xsk *xskb;
                                 ^
                                  = NULL
1 error generated.

Cheers,
Nathan

  reply	other threads:[~2021-09-28 23:15 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-22  7:56 [PATCH bpf-next 00/13] xsk: i40e: ice: introduce batching for Rx buffer allocation Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 01/13] xsk: get rid of unused entry in struct xdp_buff_xsk Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 02/13] xsk: batched buffer allocation for the pool Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 03/13] ice: use xdp_buf instead of rx_buf for xsk zero-copy Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 04/13] ice: use the xsk batched rx allocation interface Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 05/13] i40e: " Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 06/13] xsk: optimize for aligned case Magnus Karlsson
2021-09-28 23:15   ` Nathan Chancellor [this message]
2021-09-29  5:52     ` Magnus Karlsson
2021-09-29 15:33   ` kernel test robot
2021-09-22  7:56 ` [PATCH bpf-next 07/13] selftests: xsk: fix missing initialization Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 08/13] selftests: xsk: put the same buffer only once in the fill ring Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 09/13] selftests: xsk: fix socket creation retry Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 10/13] selftests: xsk: introduce pacing of traffic Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 11/13] selftests: xsk: add single packet test Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 12/13] selftests: xsk: change interleaving of packets in unaligned mode Magnus Karlsson
2021-09-22  7:56 ` [PATCH bpf-next 13/13] selftests: xsk: add frame_headroom test Magnus Karlsson
2021-09-27 22:30 ` [PATCH bpf-next 00/13] xsk: i40e: ice: introduce batching for Rx buffer allocation patchwork-bot+netdevbpf

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