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From: Josh Triplett <josh@joshtriplett.org>
To: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
Cc: Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
Subject: Re: [PATCH] nvme: Check for readiness more quickly, to speed up boot time
Date: Sun, 1 Mar 2020 01:02:39 -0800	[thread overview]
Message-ID: <20200301090239.GC216567@localhost> (raw)
In-Reply-To: <BYAPR04MB5749363E3AC8C583F5CB076786E60@BYAPR04MB5749.namprd04.prod.outlook.com>

On Sun, Mar 01, 2020 at 02:01:05AM +0000, Chaitanya Kulkarni wrote:
> Nit:- please have a look at the patch subject line and make
> sure it is not exceeding the required length.

Documentation/process/submitting-patches.rst says "no more than 70-75
characters,", and the summary here is 61. Checkpatch similarly says 75.
Is there somewhere I missed that gives a different number?

> One question though, have you seen similar kind of performance 
> improvements when system is booted ?

I tested with nvme compiled in, both with one NVMe device and two NVMe
devices, and in both cases it provided a *substantial* speedup. I didn't
test nvme compiled as a module, but in general I'd expect that if you're
trying to optimize initialization time you'd want to build it in.

> I took some numbers and couldn't see similar benefit. See [1] :-
> 
> Without :-
> 
> 714.532560-714.456099 = .076461
> 721.189886-721.110845 = .079041
> 727.836938-727.765572 = .071366
> 734.589886-734.519779 = .070107
> 741.244296-741.173503 = .070793

With numbers in this range, I don't see how you could be hitting the
100ms msleep at all, even once, which means this patch shouldn't have
any effect on the timing you're measuring.

- Josh Triplett

WARNING: multiple messages have this Message-ID (diff)
From: Josh Triplett <josh@joshtriplett.org>
To: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
Cc: Sagi Grimberg <sagi@grimberg.me>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	Jens Axboe <axboe@fb.com>, Keith Busch <kbusch@kernel.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] nvme: Check for readiness more quickly, to speed up boot time
Date: Sun, 1 Mar 2020 01:02:39 -0800	[thread overview]
Message-ID: <20200301090239.GC216567@localhost> (raw)
In-Reply-To: <BYAPR04MB5749363E3AC8C583F5CB076786E60@BYAPR04MB5749.namprd04.prod.outlook.com>

On Sun, Mar 01, 2020 at 02:01:05AM +0000, Chaitanya Kulkarni wrote:
> Nit:- please have a look at the patch subject line and make
> sure it is not exceeding the required length.

Documentation/process/submitting-patches.rst says "no more than 70-75
characters,", and the summary here is 61. Checkpatch similarly says 75.
Is there somewhere I missed that gives a different number?

> One question though, have you seen similar kind of performance 
> improvements when system is booted ?

I tested with nvme compiled in, both with one NVMe device and two NVMe
devices, and in both cases it provided a *substantial* speedup. I didn't
test nvme compiled as a module, but in general I'd expect that if you're
trying to optimize initialization time you'd want to build it in.

> I took some numbers and couldn't see similar benefit. See [1] :-
> 
> Without :-
> 
> 714.532560-714.456099 = .076461
> 721.189886-721.110845 = .079041
> 727.836938-727.765572 = .071366
> 734.589886-734.519779 = .070107
> 741.244296-741.173503 = .070793

With numbers in this range, I don't see how you could be hitting the
100ms msleep at all, even once, which means this patch shouldn't have
any effect on the timing you're measuring.

- Josh Triplett

_______________________________________________
linux-nvme mailing list
linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

  reply	other threads:[~2020-03-01  9:03 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-29  2:52 [PATCH] nvme: Check for readiness more quickly, to speed up boot time Josh Triplett
2020-02-29  2:52 ` Josh Triplett
2020-03-01  2:01 ` Chaitanya Kulkarni
2020-03-01  2:01   ` Chaitanya Kulkarni
2020-03-01  9:02   ` Josh Triplett [this message]
2020-03-01  9:02     ` Josh Triplett
2020-03-01 18:32 ` Keith Busch
2020-03-01 18:32   ` Keith Busch
2020-03-01 19:15   ` Josh Triplett
2020-03-01 19:15     ` Josh Triplett
2020-03-02 14:53     ` Keith Busch
2020-03-02 14:53       ` Keith Busch
2020-03-01 19:53   ` Chaitanya Kulkarni
2020-03-01 19:53     ` Chaitanya Kulkarni
2020-03-02 17:46 ` Sagi Grimberg
2020-03-02 17:46   ` Sagi Grimberg
2020-03-03 20:20   ` Keith Busch
2020-03-03 20:20     ` Keith Busch

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