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Mon, 13 Apr 2026 10:47:11 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list 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 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