From: Christoph Hellwig <hch@infradead.org>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
Song Liu <song@kernel.org>, Christoph Hellwig <hch@infradead.org>,
Guoqing Jiang <guoqing.jiang@linux.dev>,
Stephen Bates <sbates@raithlin.com>,
Martin Oliveira <Martin.Oliveira@eideticom.com>,
David Sloan <David.Sloan@eideticom.com>
Subject: Re: [PATCH v2 12/12] md/raid5: Pivot raid5_make_request()
Date: Wed, 20 Apr 2022 23:43:52 -0700 [thread overview]
Message-ID: <YmD9KBJtOjV+J5We@infradead.org> (raw)
In-Reply-To: <20220420195425.34911-13-logang@deltatee.com>
On Wed, Apr 20, 2022 at 01:54:25PM -0600, Logan Gunthorpe wrote:
> struct stripe_request_ctx {
> bool do_flush;
> struct stripe_head *batch_last;
> + sector_t disk_sector_done;
> + sector_t start_disk_sector;
Very nitpicky, but why use two different naming styles for the sectors
here?
> + bool first_wrap;
> + sector_t last_sector;
And especially with the last_sector here a few comments explaining
what each of the sector values mean might be useful.
I'd also keep the two bool variables together for a better structure
layout.
> + * if new_sector is less than the starting sector. Clear the
> + * boolean once the start sector is hit for the second time.
> + * When first_wrap is set, ignore the disk_sector_done.
> + */
> + if (ctx->start_disk_sector == MaxSector) {
> + ctx->start_disk_sector = new_sector;
> + } else if (new_sector < ctx->start_disk_sector) {
> + ctx->first_wrap = true;
> + } else if (new_sector == ctx->start_disk_sector) {
> + ctx->first_wrap = false;
> + ctx->start_disk_sector = 0;
> + return STRIPE_SUCCESS;
> + } else if (!ctx->first_wrap && new_sector <= ctx->disk_sector_done) {
> + return STRIPE_SUCCESS;
> + }
> +
I find this a bit confusing to read. While trying to mentally untangle
it I came up with this version instead, but it could really use some
good comments explaining each of the checks as I found your big comment
to not quite match the logic easily.
if (ctx->start_disk_sector == MaxSector) {
/*
* First loop iteration, start our state machine.
*
ctx->start_disk_sector = new_sector;
} else {
/*
* We are done if we wrapped around to the same sector.
* (???)
*/
if (new_sector == ctx->start_disk_sector) {
ctx->first_wrap = false;
ctx->start_disk_sector = 0;
return STRIPE_SUCCESS;
}
/*
* Sector before the start sector? Keep going and wrap
* around.
*/
if (new_sector < ctx->start_disk_sector) {
ctx->first_wrap = true;
} else {
// ???
if (new_sector <= ctx->disk_sector_done &&
!ctx->first_wrap)
return STRIPE_SUCCESS;
}
}
next prev parent reply other threads:[~2022-04-21 6:46 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-20 19:54 [PATCH v2 00/12] Improve Raid5 Lock Contention Logan Gunthorpe
2022-04-20 19:54 ` [PATCH v2 01/12] md/raid5: Factor out ahead_of_reshape() function Logan Gunthorpe
2022-04-21 6:07 ` Christoph Hellwig
2022-04-21 9:17 ` Paul Menzel
2022-04-21 16:05 ` Logan Gunthorpe
2022-04-21 23:33 ` Wol
2022-04-27 1:28 ` Guoqing Jiang
2022-04-27 16:07 ` Logan Gunthorpe
2022-04-28 1:49 ` Guoqing Jiang
2022-04-28 15:44 ` Logan Gunthorpe
2022-04-29 0:24 ` Guoqing Jiang
2022-04-20 19:54 ` [PATCH v2 02/12] md/raid5: Refactor raid5_make_request loop Logan Gunthorpe
2022-04-21 6:08 ` Christoph Hellwig
2022-04-27 1:32 ` Guoqing Jiang
2022-04-27 16:08 ` Logan Gunthorpe
2022-04-28 1:16 ` Guoqing Jiang
2022-04-20 19:54 ` [PATCH v2 03/12] md/raid5: Move stripe_add_to_batch_list() call out of add_stripe_bio() Logan Gunthorpe
2022-04-27 1:33 ` Guoqing Jiang
2022-04-20 19:54 ` [PATCH v2 04/12] md/raid5: Move common stripe count increment code into __find_stripe() Logan Gunthorpe
2022-04-21 6:10 ` Christoph Hellwig
2022-04-27 1:33 ` Guoqing Jiang
2022-04-20 19:54 ` [PATCH v2 05/12] md/raid5: Factor out helper from raid5_make_request() loop Logan Gunthorpe
2022-04-21 6:14 ` Christoph Hellwig
2022-04-20 19:54 ` [PATCH v2 06/12] md/raid5: Drop the do_prepare flag in raid5_make_request() Logan Gunthorpe
2022-04-21 6:15 ` Christoph Hellwig
2022-04-27 2:11 ` Guoqing Jiang
2022-04-20 19:54 ` [PATCH v2 07/12] md/raid5: Move read_seqcount_begin() into make_stripe_request() Logan Gunthorpe
2022-04-21 6:15 ` Christoph Hellwig
2022-04-27 2:13 ` Guoqing Jiang
2022-04-20 19:54 ` [PATCH v2 08/12] md/raid5: Refactor for loop in raid5_make_request() into while loop Logan Gunthorpe
2022-04-21 6:16 ` Christoph Hellwig
2022-04-20 19:54 ` [PATCH v2 09/12] md/raid5: Keep a reference to last stripe_head for batch Logan Gunthorpe
2022-04-21 6:17 ` Christoph Hellwig
2022-04-27 1:36 ` Guoqing Jiang
2022-04-27 23:27 ` Logan Gunthorpe
2022-04-20 19:54 ` [PATCH v2 10/12] md/raid5: Refactor add_stripe_bio() Logan Gunthorpe
2022-04-21 6:18 ` Christoph Hellwig
2022-04-20 19:54 ` [PATCH v2 11/12] md/raid5: Check all disks in a stripe_head for reshape progress Logan Gunthorpe
2022-04-21 6:18 ` Christoph Hellwig
2022-04-27 1:53 ` Guoqing Jiang
2022-04-27 16:11 ` Logan Gunthorpe
2022-04-20 19:54 ` [PATCH v2 12/12] md/raid5: Pivot raid5_make_request() Logan Gunthorpe
2022-04-21 6:43 ` Christoph Hellwig [this message]
2022-04-21 15:54 ` Logan Gunthorpe
2022-04-27 2:06 ` Guoqing Jiang
2022-04-27 16:18 ` Logan Gunthorpe
2022-04-28 1:32 ` Guoqing Jiang
2022-04-21 8:45 ` [PATCH v2 00/12] Improve Raid5 Lock Contention Xiao Ni
2022-04-21 16:02 ` Logan Gunthorpe
2022-04-24 8:00 ` Guoqing Jiang
2022-04-25 15:39 ` Logan Gunthorpe
2022-04-25 16:12 ` Xiao Ni
2022-04-28 21:22 ` Logan Gunthorpe
2022-04-29 0:49 ` Guoqing Jiang
2022-04-29 16:01 ` Logan Gunthorpe
2022-04-30 1:44 ` Guoqing Jiang
2022-04-24 7:53 ` Guoqing Jiang
2022-04-25 15:37 ` Logan Gunthorpe
2022-04-25 23:07 ` Song Liu
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