From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Will Deacon <will.deacon@arm.com>,
Russell King <linux@armlinux.org.uk>,
Ralf Baechle <ralf@linux-mips.org>,
Mark Salyzyn <salyzyn@android.com>,
Paul Burton <paul.burton@mips.com>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Peter Collingbourne <pcc@google.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 01/23] kernel: Standardize vdso_datapage
Date: Wed, 27 Feb 2019 14:23:02 +0000 [thread overview]
Message-ID: <3f7238b5-3357-3635-38f4-9eaa14e400c9@arm.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1902231727060.1666@nanos.tec.linutronix.de>
On 23/02/2019 16:51, Thomas Gleixner wrote:
> On Fri, 22 Feb 2019, Vincenzo Frascino wrote:
>> +/*
>> + * There is one vdso_clocksource object in vvar for each vDSO clocksource
>> + * (mono, raw). This struct is designed to keep vdso_data "cache-line friendly"
>> + * and optimal in terms of access pattern.
>> + *
>> + * Note that mask and shift are the same for mono and raw.
>> + */
>> +struct vdso_clocksource {
>> + u64 mask; /* Clocksource mask */
>> + u32 mult; /* Clocksource multiplier */
>> + u32 shift; /* Clocksource shift */
>
> Can you please get rid of the tail comments and use proper kerneldoc
> format?
>
I will fix it in v6, thanks.
>> +/*
>> + * vdso_data will be accessed by 32 and 64 bit code at the same time
>> + * so we should be careful before modifying this structure.
>> + */
>> +struct vdso_data {
>> + u32 seq; /* Timebase sequence counter */
>> +
>> + s32 clock_mode;
>> + u64 cycle_last; /* Timebase at clocksource init */
>> +
>> + struct vdso_clocksource cs[CLOCKSOURCE_BASES];
>
> Why would you need different clocksource parameters? That really bloats the
> data structure and makes the cache access pattern worse. Also the vdso
> update needs to copy the same data over and over for no value.
>
> The only clock ID which needs a different mult/shift would be
> MONOTONIC_RAW, but if we expose that through the VDSO then we really can be
> smarter than this. See incomplete and uncompilable patch below for
> reference. You get the idea.
>
Ok, thank you for providing the reference code. I will update my patches in v6
accordingly.
...
--
Regards,
Vincenzo
WARNING: multiple messages have this Message-ID (diff)
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>,
Russell King <linux@armlinux.org.uk>,
Ralf Baechle <ralf@linux-mips.org>,
Paul Burton <paul.burton@mips.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Mark Salyzyn <salyzyn@android.com>,
Peter Collingbourne <pcc@google.com>,
Shuah Khan <shuah@kernel.org>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: Re: [PATCH v5 01/23] kernel: Standardize vdso_datapage
Date: Wed, 27 Feb 2019 14:23:02 +0000 [thread overview]
Message-ID: <3f7238b5-3357-3635-38f4-9eaa14e400c9@arm.com> (raw)
Message-ID: <20190227142302.OH5ezCD5HxJSFKhwm-ZnoKfYIOW1fxQnUsS7BvRZYbg@z> (raw)
In-Reply-To: <alpine.DEB.2.21.1902231727060.1666@nanos.tec.linutronix.de>
On 23/02/2019 16:51, Thomas Gleixner wrote:
> On Fri, 22 Feb 2019, Vincenzo Frascino wrote:
>> +/*
>> + * There is one vdso_clocksource object in vvar for each vDSO clocksource
>> + * (mono, raw). This struct is designed to keep vdso_data "cache-line friendly"
>> + * and optimal in terms of access pattern.
>> + *
>> + * Note that mask and shift are the same for mono and raw.
>> + */
>> +struct vdso_clocksource {
>> + u64 mask; /* Clocksource mask */
>> + u32 mult; /* Clocksource multiplier */
>> + u32 shift; /* Clocksource shift */
>
> Can you please get rid of the tail comments and use proper kerneldoc
> format?
>
I will fix it in v6, thanks.
>> +/*
>> + * vdso_data will be accessed by 32 and 64 bit code at the same time
>> + * so we should be careful before modifying this structure.
>> + */
>> +struct vdso_data {
>> + u32 seq; /* Timebase sequence counter */
>> +
>> + s32 clock_mode;
>> + u64 cycle_last; /* Timebase at clocksource init */
>> +
>> + struct vdso_clocksource cs[CLOCKSOURCE_BASES];
>
> Why would you need different clocksource parameters? That really bloats the
> data structure and makes the cache access pattern worse. Also the vdso
> update needs to copy the same data over and over for no value.
>
> The only clock ID which needs a different mult/shift would be
> MONOTONIC_RAW, but if we expose that through the VDSO then we really can be
> smarter than this. See incomplete and uncompilable patch below for
> reference. You get the idea.
>
Ok, thank you for providing the reference code. I will update my patches in v6
accordingly.
...
--
Regards,
Vincenzo
WARNING: multiple messages have this Message-ID (diff)
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Will Deacon <will.deacon@arm.com>,
Russell King <linux@armlinux.org.uk>,
Ralf Baechle <ralf@linux-mips.org>,
Mark Salyzyn <salyzyn@android.com>,
Paul Burton <paul.burton@mips.com>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Peter Collingbourne <pcc@google.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 01/23] kernel: Standardize vdso_datapage
Date: Wed, 27 Feb 2019 14:23:02 +0000 [thread overview]
Message-ID: <3f7238b5-3357-3635-38f4-9eaa14e400c9@arm.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1902231727060.1666@nanos.tec.linutronix.de>
On 23/02/2019 16:51, Thomas Gleixner wrote:
> On Fri, 22 Feb 2019, Vincenzo Frascino wrote:
>> +/*
>> + * There is one vdso_clocksource object in vvar for each vDSO clocksource
>> + * (mono, raw). This struct is designed to keep vdso_data "cache-line friendly"
>> + * and optimal in terms of access pattern.
>> + *
>> + * Note that mask and shift are the same for mono and raw.
>> + */
>> +struct vdso_clocksource {
>> + u64 mask; /* Clocksource mask */
>> + u32 mult; /* Clocksource multiplier */
>> + u32 shift; /* Clocksource shift */
>
> Can you please get rid of the tail comments and use proper kerneldoc
> format?
>
I will fix it in v6, thanks.
>> +/*
>> + * vdso_data will be accessed by 32 and 64 bit code at the same time
>> + * so we should be careful before modifying this structure.
>> + */
>> +struct vdso_data {
>> + u32 seq; /* Timebase sequence counter */
>> +
>> + s32 clock_mode;
>> + u64 cycle_last; /* Timebase at clocksource init */
>> +
>> + struct vdso_clocksource cs[CLOCKSOURCE_BASES];
>
> Why would you need different clocksource parameters? That really bloats the
> data structure and makes the cache access pattern worse. Also the vdso
> update needs to copy the same data over and over for no value.
>
> The only clock ID which needs a different mult/shift would be
> MONOTONIC_RAW, but if we expose that through the VDSO then we really can be
> smarter than this. See incomplete and uncompilable patch below for
> reference. You get the idea.
>
Ok, thank you for providing the reference code. I will update my patches in v6
accordingly.
...
--
Regards,
Vincenzo
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next prev parent reply other threads:[~2019-02-27 14:23 UTC|newest]
Thread overview: 178+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-22 12:24 [PATCH v5 00/23] Unify vDSOs across more architectures Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 01/23] kernel: Standardize vdso_datapage Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:58 ` Mark Rutland
2019-02-22 12:58 ` Mark Rutland
2019-02-22 12:58 ` Mark Rutland
2019-02-23 16:51 ` Thomas Gleixner
2019-02-23 16:51 ` Thomas Gleixner
2019-02-23 16:51 ` Thomas Gleixner
2019-02-27 14:23 ` Vincenzo Frascino [this message]
2019-02-27 14:23 ` Vincenzo Frascino
2019-02-27 14:23 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 02/23] kernel: Define gettimeofday vdso common code Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 13:34 ` Mark Rutland
2019-02-22 13:34 ` Mark Rutland
2019-02-22 13:34 ` Mark Rutland
2019-02-22 13:49 ` Arnd Bergmann
2019-02-22 13:49 ` Arnd Bergmann
2019-02-22 13:49 ` Arnd Bergmann
2019-02-22 14:36 ` Arnd Bergmann
2019-02-22 14:36 ` Arnd Bergmann
2019-02-22 14:36 ` Arnd Bergmann
2019-02-27 14:52 ` Vincenzo Frascino
2019-02-27 14:52 ` Vincenzo Frascino
2019-02-27 14:52 ` Vincenzo Frascino
2019-02-28 9:29 ` Arnd Bergmann
2019-02-28 9:29 ` Arnd Bergmann
2019-02-28 9:29 ` Arnd Bergmann
2019-02-28 11:58 ` [PATCH 1/2] vdso: use fixed-size time types Arnd Bergmann
2019-02-28 11:58 ` Arnd Bergmann
2019-02-28 11:58 ` Arnd Bergmann
2019-02-28 11:58 ` [PATCH 2/2] vdso: add clock_gettime64 Arnd Bergmann
2019-02-28 11:58 ` Arnd Bergmann
2019-02-28 11:58 ` Arnd Bergmann
2019-02-28 13:42 ` [PATCH 1/2] vdso: use fixed-size time types Thomas Gleixner
2019-02-28 13:42 ` Thomas Gleixner
2019-02-28 13:42 ` Thomas Gleixner
2019-02-28 13:45 ` Vincenzo Frascino
2019-02-28 13:45 ` Vincenzo Frascino
2019-02-28 13:45 ` Vincenzo Frascino
2019-02-23 10:34 ` [PATCH v5 02/23] kernel: Define gettimeofday vdso common code Thomas Gleixner
2019-02-23 10:34 ` Thomas Gleixner
2019-02-23 10:34 ` Thomas Gleixner
2019-02-25 14:09 ` Vincenzo Frascino
2019-02-25 14:09 ` Vincenzo Frascino
2019-02-25 14:09 ` Vincenzo Frascino
2019-02-23 17:31 ` Thomas Gleixner
2019-02-23 17:31 ` Thomas Gleixner
2019-02-23 17:31 ` Thomas Gleixner
2019-02-27 13:47 ` Vincenzo Frascino
2019-02-27 13:47 ` Vincenzo Frascino
2019-02-27 13:47 ` Vincenzo Frascino
2019-02-27 15:49 ` Thomas Gleixner
2019-02-27 15:49 ` Thomas Gleixner
2019-02-27 15:49 ` Thomas Gleixner
2019-02-27 16:06 ` Vincenzo Frascino
2019-02-27 16:06 ` Vincenzo Frascino
2019-02-27 16:06 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 03/23] arm64: Build vDSO with -ffixed-x18 Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 04/23] arm64: Substitute gettimeofday with C implementation Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 13:42 ` Mark Rutland
2019-02-22 13:42 ` Mark Rutland
2019-02-22 13:42 ` Mark Rutland
2019-02-22 12:24 ` [PATCH v5 05/23] arm64: compat: Alloc separate pages for vectors and sigpage Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 06/23] arm64: compat: Split kuser32 Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 07/23] arm64: compat: Refactor aarch32_alloc_vdso_pages() Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 08/23] arm64: compat: Add KUSER_HELPERS config option Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 14:04 ` Mark Rutland
2019-02-22 14:04 ` Mark Rutland
2019-02-22 14:04 ` Mark Rutland
2019-02-22 14:09 ` Russell King - ARM Linux admin
2019-02-22 14:09 ` Russell King - ARM Linux admin
2019-02-22 14:09 ` Russell King - ARM Linux admin
2019-02-26 12:10 ` Vincenzo Frascino
2019-02-26 12:10 ` Vincenzo Frascino
2019-02-26 12:10 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 09/23] arm64: compat: Add missing syscall numbers Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 10/23] arm64: compat: Expose signal related structures Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 11/23] arm64: compat: Generate asm offsets for signals Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 14:22 ` Mark Rutland
2019-02-22 14:22 ` Mark Rutland
2019-02-22 14:22 ` Mark Rutland
2019-02-22 12:24 ` [PATCH v5 12/23] lib: vdso: Add compat support Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 13/23] arm64: compat: Add vDSO Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 14:32 ` Mark Rutland
2019-02-22 14:32 ` Mark Rutland
2019-02-22 14:32 ` Mark Rutland
2019-02-22 12:24 ` [PATCH v5 14/23] arm64: Refactor vDSO code Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 14:37 ` Mark Rutland
2019-02-22 14:37 ` Mark Rutland
2019-02-22 14:37 ` Mark Rutland
2019-02-22 12:24 ` [PATCH v5 15/23] arm64: compat: vDSO setup for compat layer Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 16/23] arm64: elf: vDSO code page discovery Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 17/23] arm64: compat: Get sigreturn trampolines from vDSO Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 18/23] arm64: Add vDSO compat support Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 19/23] arm64: Enable compat vDSO support Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 14:39 ` Mark Rutland
2019-02-22 14:39 ` Mark Rutland
2019-02-22 14:39 ` Mark Rutland
2019-02-22 14:41 ` Mark Rutland
2019-02-22 14:41 ` Mark Rutland
2019-02-22 14:41 ` Mark Rutland
2019-02-22 12:24 ` [PATCH v5 20/23] arm: Add support for generic vDSO Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 21/23] mips: " Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 22/23] x86: " Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-23 10:45 ` Thomas Gleixner
2019-02-23 10:45 ` Thomas Gleixner
2019-02-23 10:45 ` Thomas Gleixner
2019-02-27 16:18 ` Vincenzo Frascino
2019-02-27 16:18 ` Vincenzo Frascino
2019-02-27 16:18 ` Vincenzo Frascino
2019-02-22 12:24 ` [PATCH v5 23/23] kselftest: Extend vDSO selftest Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-22 12:24 ` Vincenzo Frascino
2019-02-23 17:39 ` [PATCH v5 00/23] Unify vDSOs across more architectures Thomas Gleixner
2019-02-23 17:39 ` Thomas Gleixner
2019-02-23 17:39 ` Thomas Gleixner
2019-02-28 11:40 ` Arnd Bergmann
2019-02-28 11:40 ` Arnd Bergmann
2019-02-28 12:09 ` Vincenzo Frascino
2019-02-28 12:09 ` Vincenzo Frascino
2019-02-28 12:38 ` Arnd Bergmann
2019-02-28 12:38 ` Arnd Bergmann
2019-02-28 12:38 ` Arnd Bergmann
2019-02-28 12:42 ` Vincenzo Frascino
2019-02-28 12:42 ` Vincenzo Frascino
2019-02-28 12:42 ` Vincenzo Frascino
2019-02-28 13:54 ` Arnd Bergmann
2019-02-28 13:54 ` Arnd Bergmann
2019-02-28 13:54 ` Arnd Bergmann
2019-02-28 15:51 ` Vincenzo Frascino
2019-02-28 15:51 ` Vincenzo Frascino
2019-02-28 15:51 ` Vincenzo Frascino
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