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([2001:a61:133d:b101:9ea2:16fa:3380:8e40]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-442f39e8545sm23038825e9.31.2025.05.14.02.34.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 May 2025 02:34:22 -0700 (PDT) Message-ID: Date: Wed, 14 May 2025 11:34:21 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] USB: core: add a memory pool to urb for host-controller private data To: Greg KH , David Wang <00107082@163.com> Cc: mathias.nyman@intel.com, stern@rowland.harvard.edu, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org References: <20250513113817.11962-1-00107082@163.com> <20250514064455.5488-1-00107082@163.com> <2025051405-glare-crazily-a9fa@gregkh> Content-Language: en-US From: Oliver Neukum In-Reply-To: <2025051405-glare-crazily-a9fa@gregkh> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14.05.25 09:29, Greg KH wrote: > No, this isn't necessarily true at all. Allocations are fast, and if we > free/allocate things quickly, it's even faster. USB is limited by the > hardware throughput, which is _very_ slow compared to memory accesses of > the allocator. If and only if we do not trigger disk IO. If you really want to give this patch a good performance testing you'd have to do it under memory pressure. Regards Oliver