| Message ID | 20210305094113.413544-1-bjorn.topel@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | load-acquire/store-release barriers for AF_XDP rings | expand |
Björn Töpel <bjorn.topel@gmail.com> writes: > This two-patch series introduces load-acquire/store-release barriers > for the AF_XDP rings. > > For most contemporary architectures, this is more effective than a > SPSC ring based on smp_{r,w,}mb() barriers. More importantly, > load-acquire/store-release semantics make the ring code easier to > follow. > > This is effectively the change done in commit 6c43c091bdc5 > ("documentation: Update circular buffer for > load-acquire/store-release"), but for the AF_XDP rings. > > Both libbpf and the kernel-side are updated. > > Full details are outlined in the commits! > > Thanks to the LKMM-folks (Paul/Alan/Will) for helping me out in this > complicated matter! > > @Andrii I kept the barriers in libbpf_util.h to separate userfacing > APIs (xsk.h) from internals. > > @Toke I kept "barriers" but reworded. Acquire/release are also > barriers. Right, that text is better - thanks! Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Hello: This series was applied to bpf/bpf-next.git (refs/heads/master): On Fri, 5 Mar 2021 10:41:11 +0100 you wrote: > This two-patch series introduces load-acquire/store-release barriers > for the AF_XDP rings. > > For most contemporary architectures, this is more effective than a > SPSC ring based on smp_{r,w,}mb() barriers. More importantly, > load-acquire/store-release semantics make the ring code easier to > follow. > > [...] Here is the summary with links: - [bpf-next,v2,1/2] xsk: update rings for load-acquire/store-release barriers https://git.kernel.org/bpf/bpf-next/c/057e8fb782c1 - [bpf-next,v2,2/2] libbpf, xsk: add libbpf_smp_store_release libbpf_smp_load_acquire https://git.kernel.org/bpf/bpf-next/c/60d0e5fdbdf6 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
This two-patch series introduces load-acquire/store-release barriers for the AF_XDP rings. For most contemporary architectures, this is more effective than a SPSC ring based on smp_{r,w,}mb() barriers. More importantly, load-acquire/store-release semantics make the ring code easier to follow. This is effectively the change done in commit 6c43c091bdc5 ("documentation: Update circular buffer for load-acquire/store-release"), but for the AF_XDP rings. Both libbpf and the kernel-side are updated. Full details are outlined in the commits! Thanks to the LKMM-folks (Paul/Alan/Will) for helping me out in this complicated matter! @Andrii I kept the barriers in libbpf_util.h to separate userfacing APIs (xsk.h) from internals. @Toke I kept "barriers" but reworded. Acquire/release are also barriers. @Will I'd really appreciate if you could take a look this change. Changelog v1[1]->v2: * Expanded the commit message for patch 1, and included the LKMM litmus tests. Hopefully this clear things up. (Daniel) * Clarified why the smp_mb()/smp_load_acquire() is not needed in (A); control dependency with load to store. (Toke) [1] https://lore.kernel.org/bpf/20210301104318.263262-1-bjorn.topel@gmail.com/ Thanks, Björn Björn Töpel (2): xsk: update rings for load-acquire/store-release barriers libbpf, xsk: add libbpf_smp_store_release libbpf_smp_load_acquire net/xdp/xsk_queue.h | 30 +++++++--------- tools/lib/bpf/libbpf_util.h | 72 +++++++++++++++++++++++++------------ tools/lib/bpf/xsk.h | 17 +++------ 3 files changed, 68 insertions(+), 51 deletions(-) base-commit: bce8623135fbe54bd86797df72cb85bfe4118b6e