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Mon, 13 Apr 2026 10:47:11 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface MIME-Version: 1.0 X-ThreadId: A4mZ2Su1YSkV Date: Mon, 13 Apr 2026 16:46:30 +0200 From: "Arnd Bergmann" To: "Thomas Gleixner" , LKML Cc: "Theodore Ts'o" , linux-ext4@vger.kernel.org, x86@kernel.org, "Baolu Lu" , iommu@lists.linux.dev, "Michael Grzeschik" , Netdev , linux-wireless@vger.kernel.org, "Herbert Xu" , linux-crypto@vger.kernel.org, "Vlastimil Babka (SUSE)" , linux-mm@kvack.org, "David Woodhouse" , "Bernie Thompson" , linux-fbdev@vger.kernel.org, "Andrew Morton" , "Uladzislau Rezki (Sony)" , "Marco Elver" , "Dmitry Vyukov" , kasan-dev@googlegroups.com, "Andrey Ryabinin" , "Thomas Sailer" , linux-hams@vger.kernel.org, "Jason A . Donenfeld" , "Richard Henderson" , linux-alpha@vger.kernel.org, "Russell King" , linux-arm-kernel@lists.infradead.org, "Catalin Marinas" , "Huacai Chen" , loongarch@lists.linux.dev, "Geert Uytterhoeven" , linux-m68k@lists.linux-m68k.org, "Dinh Nguyen" , "Jonas Bonn" , "linux-openrisc@vger.kernel.org" , "Helge Deller" , linux-parisc@vger.kernel.org, "Michael Ellerman" , linuxppc-dev@lists.ozlabs.org, "Paul Walmsley" , linux-riscv@lists.infradead.org, "Heiko Carstens" , linux-s390@vger.kernel.org, "David S . Miller" , sparclinux@vger.kernel.org Message-Id: <90a889aa-f204-4ea8-8642-6752aa1955d8@app.fastmail.com> In-Reply-To: <20260410120318.727211419@kernel.org> References: <20260410120044.031381086@kernel.org> <20260410120318.727211419@kernel.org> Subject: Re: [patch 17/38] ext4: Replace get_cycles() usage with ktime_get() Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: 67ibzuajjgkyxug5npx89m93wggg9ptu X-Rspamd-Queue-Id: 8ABDB4000A X-Rspamd-Server: rspam09 X-HE-Tag: 1776091634-877297 X-HE-Meta: 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 JvJ2+GQi ybUFZ7/EfZwkqUjnZPfmhTQOFwF8oCcXXGp+Fl4SrN6Bq5OPWsFKzM9avMCRvXQ5SCJPYmiZKrES3Y0EJ2uHDU8UsXyYmWr/Cu7SruVvvA4XGq0MPi7Izrr8qH2U4eJWb0BlZLI6XeK2aZmvuPhmG7DMUu0KzkNvp0gIN/n7m5eKNXXvAppxsTSEicl5hLIlRY/5ITF6OXHT5aLC5IhyBb66BlbwJ+64msTh+JURWXuyr3d8cPQQsEE5nzpq1PowrasAwP4oTZoEBIuQJleS6FOhptQehZWOUz6t4Q5Dhmbe3h78fRPHtrij6HKvnlQJZfxeiYeY/r1dsHJ2YkZx6/S9QXo0NjCR9LPj4E6fSH7ANb+I1U62VHqBNh9ax4Cem2PA+OUMCuET/RSs4zCCC3qNVXA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Apr 10, 2026, at 14:19, Thomas Gleixner wrote: > get_cycles() is not guaranteed to be functional on all systems/platforms > and the values returned are unitless and not easy to map to something > useful. > > Use ktime_get() instead, which provides nanosecond timestamps and is > functional everywhere. > > This is part of a larger effort to limit get_cycles() usage to low level > architecture code. > > Signed-off-by: Thomas Gleixner > Cc: "Theodore Ts'o" > Cc: linux-ext4@vger.kernel.org I think this is technically an ABI chance, since the time difference gets exported through procfs, but the new version is clearly the right thing to do since it replaces a hardware specific value with a portable one. Arnd