From d00106bbdfa82732c23cba44491c38f8c410d865 Mon Sep 17 00:00:00 2001 From: Anna-Maria Behnsen Date: Mon, 1 Jul 2024 16:47:55 +0200 Subject: [PATCH] vdso: Add comment about reason for vdso struct ordering struct vdso_data is optimized for fast access to the often required struct members. The optimization is not documented in the struct description but it should be kept in mind, when working with the vdso_data struct. Add a comment to the struct description. Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Reviewed-by: Vincenzo Frascino Link: https://lore.kernel.org/r/20240701-vdso-cleanup-v1-2-36eb64e7ece2@linutronix.de --- include/vdso/datapage.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h index d04d394db064..7647e0946f50 100644 --- a/include/vdso/datapage.h +++ b/include/vdso/datapage.h @@ -77,6 +77,10 @@ struct vdso_timestamp { * vdso_data will be accessed by 64 bit and compat code at the same time * so we should be careful before modifying this structure. * + * The ordering of the struct members is optimized to have fast access to the + * often required struct members which are related to CLOCK_REALTIME and + * CLOCK_MONOTONIC. This information is stored in the first cache lines. + * * @basetime is used to store the base time for the system wide time getter * VVAR page. *