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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43cf515c580sm60622075e9.15.2025.03.10.15.15.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Mar 2025 15:15:50 -0700 (PDT) Date: Mon, 10 Mar 2025 22:15:48 +0000 From: David Laight To: arthur@arthurfabre.com Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, jakub@cloudflare.com, hawk@kernel.org, yan@cloudflare.com, jbrandeburg@cloudflare.com, thoiland@redhat.com, lbiancon@redhat.com, Arthur Fabre Subject: Re: [PATCH RFC bpf-next 05/20] trait: Replace memcpy calls with inline copies Message-ID: <20250310221548.1c198a2b@pumpkin> In-Reply-To: <20250305-afabre-traits-010-rfc2-v1-5-d0ecfb869797@cloudflare.com> References: <20250305-afabre-traits-010-rfc2-v1-0-d0ecfb869797@cloudflare.com> <20250305-afabre-traits-010-rfc2-v1-5-d0ecfb869797@cloudflare.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 05 Mar 2025 15:32:02 +0100 arthur@arthurfabre.com wrote: > From: Arthur Fabre > > When copying trait values to or from the caller, the size isn't a > constant so memcpy() ends up being a function call. > > Replace it with an inline implementation that only handles the sizes we > support. > > We store values "packed", so they won't necessarily be 4 or 8 byte > aligned. > > Setting and getting traits is roughly ~40% faster. > > Signed-off-by: Arthur Fabre > --- > include/net/trait.h | 25 +++++++++++++++++++------ > 1 file changed, 19 insertions(+), 6 deletions(-) > > diff --git a/include/net/trait.h b/include/net/trait.h > index 536b8a17dbbc091b4d1a4d7b4b21c1e36adea86a..d4581a877bd57a32e2ad032147c906764d6d37f8 100644 > --- a/include/net/trait.h > +++ b/include/net/trait.h > @@ -7,6 +7,7 @@ > #include > #include > #include > +#include > > /* Traits are a very limited KV store, with: > * - 64 keys (0-63). > @@ -145,23 +146,23 @@ int trait_set(void *traits, void *hard_end, u64 key, const void *val, u64 len, u > memmove(traits + off + len, traits + off, traits_size(traits) - off); > } > > - /* Set our value. */ > - memcpy(traits + off, val, len); > - > - /* Store our length in header. */ > u64 encode_len = 0; > - > switch (len) { > case 2: > + /* Values are least two bytes, so they'll be two byte aligned */ > + *(u16 *)(traits + off) = *(u16 *)val; > encode_len = 1; > break; > case 4: > + put_unaligned(*(u32 *)val, (u32 *)(traits + off)); > encode_len = 2; > break; > case 8: > + put_unaligned(*(u64 *)val, (u64 *)(traits + off)); > encode_len = 3; > break; > } > + > h->high |= (encode_len >> 1) << key; > h->low |= (encode_len & 1) << key; > return 0; > @@ -201,7 +202,19 @@ int trait_get(void *traits, u64 key, void *val, u64 val_len) > if (real_len > val_len) > return -ENOSPC; > > - memcpy(val, traits + off, real_len); > + switch (real_len) { > + case 2: > + /* Values are least two bytes, so they'll be two byte aligned */ > + *(u16 *)val = *(u16 *)(traits + off); > + break; > + case 4: > + *(u32 *)val = get_unaligned((u32 *)(traits + off)); > + break; > + case 8: > + *(u64 *)val = get_unaligned((u64 *)(traits + off)); > + break; Should there be a 'default' in here? Possibly just 'return 0'? > + } > + > return real_len; > } > >