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Date: Wed, 15 Jan 2020 14:09:54 -0800
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Yonghong Song <yhs@...com>
Cc: Brian Vazquez <brianvv@...gle.com>,
Brian Vazquez <brianvv.kernel@...il.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
"David S . Miller" <davem@...emloft.net>,
Andrii Nakryiko <andrii.nakryiko@...il.com>,
Stanislav Fomichev <sdf@...gle.com>,
Petar Penkov <ppenkov@...gle.com>,
Willem de Bruijn <willemb@...gle.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"bpf@...r.kernel.org" <bpf@...r.kernel.org>
Subject: Re: [PATCH v5 bpf-next 0/9] add bpf batch ops to process more than 1 elem
On Wed, Jan 15, 2020 at 12:13 PM Yonghong Song <yhs@...com> wrote:
>
>
>
> On 1/15/20 10:42 AM, Brian Vazquez wrote:
> > This patch series introduce batch ops that can be added to bpf maps to
> > lookup/lookup_and_delete/update/delete more than 1 element at the time,
> > this is specially useful when syscall overhead is a problem and in case
> > of hmap it will provide a reliable way of traversing them.
> >
> > The implementation inclues a generic approach that could potentially be
> > used by any bpf map and adds it to arraymap, it also includes the specific
> > implementation of hashmaps which are traversed using buckets instead
> > of keys.
> >
> > The bpf syscall subcommands introduced are:
> >
> > BPF_MAP_LOOKUP_BATCH
> > BPF_MAP_LOOKUP_AND_DELETE_BATCH
> > BPF_MAP_UPDATE_BATCH
> > BPF_MAP_DELETE_BATCH
> >
> > The UAPI attribute is:
> >
> > struct { /* struct used by BPF_MAP_*_BATCH commands */
> > __aligned_u64 in_batch; /* start batch,
> > * NULL to start from beginning
> > */
> > __aligned_u64 out_batch; /* output: next start batch */
> > __aligned_u64 keys;
> > __aligned_u64 values;
> > __u32 count; /* input/output:
> > * input: # of key/value
> > * elements
> > * output: # of filled elements
> > */
> > __u32 map_fd;
> > __u64 elem_flags;
> > __u64 flags;
> > } batch;
> >
> >
> > in_batch and out_batch are only used for lookup and lookup_and_delete since
> > those are the only two operations that attempt to traverse the map.
> >
> > update/delete batch ops should provide the keys/values that user wants
> > to modify.
> >
> > Here are the previous discussions on the batch processing:
> > - https://lore.kernel.org/bpf/20190724165803.87470-1-brianvv@google.com/
> > - https://lore.kernel.org/bpf/20190829064502.2750303-1-yhs@fb.com/
> > - https://lore.kernel.org/bpf/20190906225434.3635421-1-yhs@fb.com/
> >
> > Changelog sinve v4:
> > - Remove unnecessary checks from libbpf API (Andrii Nakryiko)
> > - Move DECLARE_LIBBPF_OPTS with all var declarations (Andrii Nakryiko)
> > - Change bucket internal buffer size to 5 entries (Yonghong Song)
> > - Fix some minor bugs in hashtab batch ops implementation (Yonghong Song)
> >
> > Changelog sinve v3:
> > - Do not use copy_to_user inside atomic region (Yonghong Song)
> > - Use _opts approach on libbpf APIs (Andrii Nakryiko)
> > - Drop generic_map_lookup_and_delete_batch support
> > - Free malloc-ed memory in tests (Yonghong Song)
> > - Reverse christmas tree (Yonghong Song)
> > - Add acked labels
> >
> > Changelog sinve v2:
> > - Add generic batch support for lpm_trie and test it (Yonghong Song)
> > - Use define MAP_LOOKUP_RETRIES for retries (John Fastabend)
> > - Return errors directly and remove labels (Yonghong Song)
> > - Insert new API functions into libbpf alphabetically (Yonghong Song)
> > - Change hlist_nulls_for_each_entry_rcu to
> > hlist_nulls_for_each_entry_safe in htab batch ops (Yonghong Song)
> >
> > Changelog since v1:
> > - Fix SOB ordering and remove Co-authored-by tag (Alexei Starovoitov)
> >
> > Changelog since RFC:
> > - Change batch to in_batch and out_batch to support more flexible opaque
> > values to iterate the bpf maps.
> > - Remove update/delete specific batch ops for htab and use the generic
> > implementations instead.
> >
> > Brian Vazquez (5):
> > bpf: add bpf_map_{value_size,update_value,map_copy_value} functions
> > bpf: add generic support for lookup batch op
> > bpf: add generic support for update and delete batch ops
> > bpf: add lookup and update batch ops to arraymap
> > selftests/bpf: add batch ops testing to array bpf map
> >
> > Yonghong Song (4):
> > bpf: add batch ops to all htab bpf map
> > tools/bpf: sync uapi header bpf.h
> > libbpf: add libbpf support to batch ops
> > selftests/bpf: add batch ops testing for htab and htab_percpu map
> >
> > include/linux/bpf.h | 18 +
> > include/uapi/linux/bpf.h | 21 +
> > kernel/bpf/arraymap.c | 2 +
> > kernel/bpf/hashtab.c | 264 +++++++++
> > kernel/bpf/syscall.c | 554 ++++++++++++++----
> > tools/include/uapi/linux/bpf.h | 21 +
> > tools/lib/bpf/bpf.c | 58 ++
> > tools/lib/bpf/bpf.h | 22 +
> > tools/lib/bpf/libbpf.map | 4 +
> > .../bpf/map_tests/array_map_batch_ops.c | 129 ++++
> > .../bpf/map_tests/htab_map_batch_ops.c | 283 +++++++++
> > 11 files changed, 1248 insertions(+), 128 deletions(-)
> > create mode 100644 tools/testing/selftests/bpf/map_tests/array_map_batch_ops.c
> > create mode 100644 tools/testing/selftests/bpf/map_tests/htab_map_batch_ops.c
>
> Thanks for the work! LGTM. Ack for the whole series.
>
> Acked-by: Yonghong Song <yhs@...com>
Applied. Thanks!
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