From: Charles Keepax <ckeepax@opensource.cirrus.com>
To: Nicholas Mc Guire <der.herr@hofr.at>
Cc: "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
Nicholas Mc Guire <hofrat@osadl.org>,
Stephen Boyd <sboyd@codeaurora.org>
Subject: Re: [PATCH review for 4.4 12/47] clk: wm831x: fix usleep_range with bad range
Date: Fri, 6 Oct 2017 11:00:59 +0100 [thread overview]
Message-ID: <20171006100059.725roshck2lwk25z@localhost.localdomain> (raw)
In-Reply-To: <20171006080323.GA25724@osadl.at>
On Fri, Oct 06, 2017 at 08:03:23AM +0000, Nicholas Mc Guire wrote:
> On Sun, Sep 24, 2017 at 12:18:12AM +0000, Levin, Alexander (Sasha Levin) wrote:
> > On Fri, Sep 22, 2017 at 09:46:28AM +0100, Charles Keepax wrote:
> > >On Wed, Sep 20, 2017 at 04:45:02AM +0000, Levin, Alexander (Sasha Levin) wrote:
> > >Does this patch really make sense for stable, isn't this really
> > >just a small optimisation? The patch is pretty harmless so I
> > >can't see applying it causing any problems, just curious what
> > >problems not having it is causing.
> >
> > Looking back at this, I think I misunderstood a scenario in the scheduler this might be causing. What you say makes sense, I'll drop it.
> >
>
> sorry for the delay - was off-line.
>
> The motivation is that if usleep_range is used with min==max
> then it allows no consolidation of highresolution timers at all
> but as this is not an atomic code-section anyway it is not sensible
> to force a precise timer - the pach relaxes the timing so that
> the highrestimers load can be reduced.
>
> Technically this should have no effect at all as the jitter of
> the system is probably a lot higher than the range given anyway
> but the range allows optimization of highresolution timers.
>
Indeed, which is why it is a good commit that was merged into
mainline.
> So basically you are right its an optimization only but it is not
> only relevant to keep the highrestimers well optimized it is also
> the recommendation in the kernel documentation and since there is
> not drawback with this optimization I think it should be considered even
> if it is not important.
>
But my understanding is only patches to fix significant issues
should be backported to stable, this doesn't really do that. As
you say it is fairly harmless though, so I can't see it causing
any problems so I am certainly not nak-ing it.
Thanks,
Charles
next prev parent reply other threads:[~2017-10-06 10:01 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-20 4:44 [PATCH review for 4.4 01/47] drm_fourcc: Fix DRM_FORMAT_MOD_LINEAR #define Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 03/47] GFS2: Fix reference to ERR_PTR in gfs2_glock_iter_next Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 04/47] RDS: RDMA: Fix the composite message user notification Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 05/47] ARM: dts: r8a7790: Use R-Car Gen 2 fallback binding for msiof nodes Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 02/47] drm: bridge: add DT bindings for TI ths8135 Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 07/47] MIPS: kexec: Do not reserve invalid crashkernel memory on boot Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 09/47] igb: re-assign hw address pointer on reset after PCI error Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 06/47] MIPS: Ensure bss section ends on a long-aligned address Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 08/47] MIPS: ralink: Fix incorrect assignment on ralink_soc Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 12/47] clk: wm831x: fix usleep_range with bad range Levin, Alexander (Sasha Levin)
2017-09-22 8:46 ` Charles Keepax
2017-09-24 0:18 ` Levin, Alexander (Sasha Levin)
2017-10-06 8:03 ` Nicholas Mc Guire
2017-10-06 10:00 ` Charles Keepax [this message]
2017-09-20 4:45 ` [PATCH review for 4.4 11/47] sh_eth: use correct name for ECMR_MPDE bit Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 13/47] hwmon: (gl520sm) Fix overflows and crash seen when writing into limit attributes Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 10/47] extcon: axp288: Use vbus-valid instead of -present to determine cable presence Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 15/47] iio: adc: hx711: Add DT binding for avia,hx711 Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 14/47] iio: adc: axp288: Drop bogus AXP288_ADC_TS_PIN_CTRL register modifications Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 17/47] tty: goldfish: Fix a parameter of a call to free_irq Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 16/47] ARM: 8635/1: nommu: allow enabling REMAP_VECTORS_TO_RAM Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 21/47] drm/amdkfd: fix improper return value on error Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 18/47] IB/ipoib: Fix deadlock over vlan_mutex Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 19/47] IB/ipoib: rtnl_unlock can not come after free_netdev Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 20/47] IB/ipoib: Replace list_del of the neigh->list with list_del_init Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 23/47] USB: serial: mos7840: fix control-message error handling Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 22/47] USB: serial: mos7720: " Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 24/47] pinctrl: mvebu: Use seq_puts() in mvebu_pinconf_group_dbg_show() Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 25/47] partitions/efi: Fix integer overflow in GPT size calculation Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 29/47] ASoC: dapm: fix some pointer error handling Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 27/47] audit: log 32-bit socketcalls Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 28/47] usb: chipidea: vbus event may exist before starting gadget Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 26/47] ASoC: dapm: handle probe deferrals Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 31/47] net: core: Prevent from dereferencing null pointer when releasing SKB Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 32/47] net/packet: check length in getsockopt() called with PACKET_HDRLEN Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 30/47] MIPS: Lantiq: Fix another request_mem_region() return code check Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 33/47] team: fix memory leaks Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 35/47] mmc: sdio: fix alignment issue in struct sdio_func Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 37/47] netfilter: invoke synchronize_rcu after set the _hook_ to NULL Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 34/47] usb: plusb: Add support for PL-27A1 Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 36/47] bridge: netlink: register netdevice before executing changelink Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 38/47] MIPS: IRQ Stack: Unwind IRQ stack onto task stack Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 40/47] netfilter: nfnl_cthelper: fix incorrect helper->expect_class_max Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 41/47] parisc: perf: Fix potential NULL pointer dereference Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 39/47] [media] exynos-gsc: Do not swap cb/cr for semi planar formats Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 43/47] rds: ib: add error handle Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 42/47] iommu/io-pgtable-arm: Check for leaf entry before dereferencing it Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 45/47] i2c: meson: fix wrong variable usage in meson_i2c_put_data Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 44/47] md/raid10: submit bio directly to replacement disk Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 46/47] xfs: remove kmem_zalloc_greedy Levin, Alexander (Sasha Levin)
2017-09-20 4:45 ` [PATCH review for 4.4 47/47] libata: transport: Remove circular dependency at free time Levin, Alexander (Sasha Levin)
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