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Wed, 04 Nov 2026 10:02:04 -0800 (PST) Received: from localhost ([153.61.198.252]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8b1d9403d9esm98837b3a.52.2026.11.04.10.02.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Nov 2026 10:02:02 -0800 (PST) Content-Type: text/plain; charset=UTF-8 Date: Wed, 04 Nov 2026 18:02:02 +0000 Message-Id: Cc: , , Subject: Re: [PATCH bpf-next v3 00/14] bpf: A stack in arena From: "Alexei Starovoitov" To: "Kumar Kartikeya Dwivedi" , In-Reply-To: References: <20261104012401.1354861-1-alexei.starovoitov@gmail.com> Content-Transfer-Encoding: 8bit X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 On Tue, Nov 03, 2026 at 11:35 PM Kumar Kartikeya Dwivedi wrote: >> The price against libarena with __arena: two times more casts, JITed code >> +18%, arena_malloc() +7%. > > Could you elaborate on this? Are the extra casts due to the fact that globals, > heaps, and locals on the stack are moving to arena memory? exactly. > My understanding is > that 1-1, the compiler approach is still more efficient in terms of the casts > emitted (and 32-bit narrowing) vs BPF_F_ARENA_SCALAR. Right. llvm adding casts is a clear win over BPF_F_ARENA_SCALAR.