From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
To: Rafael Aquini <aquini@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, hughd@google.com, shli@kernel.org,
kzak@redhat.com, jmoyer@redhat.com, riel@redhat.com,
lwoodman@redhat.com, mgorman@suse.de, kosaki.motohiro@gmail.com
Subject: Re: [RFC PATCH 02/02] swapon: add "cluster-discard" support
Date: Mon, 20 May 2013 21:02:43 -0400 [thread overview]
Message-ID: <519AC7B3.5060902@gmail.com> (raw)
In-Reply-To: <398ace0dd3ca1283372b3aad3fceeee59f6897d7.1369084886.git.aquini@redhat.com>
> +.B "\-c, \-\-cluster\-discard"
> +Swapping will discard clusters of swap pages in between freeing them
> +and re-writing to them, if the swap device supports that. This option
> +also implies the
> +.I \-d, \-\-discard
> +swapon flag.
I'm not sure this is good idea. Why can't we make these flags orthogonal?
> /* If true, don't complain if the device/file doesn't exist */
> static int ifexists;
> @@ -570,8 +574,11 @@ static int do_swapon(const char *orig_special, int prio,
> << SWAP_FLAG_PRIO_SHIFT);
> }
> #endif
> - if (fl_discard)
> + if (fl_discard) {
> flags |= SWAP_FLAG_DISCARD;
> + if (fl_discard > 1)
> + flags |= SWAP_FLAG_DISCARD_CLUSTER;
This is not enough, IMHO. When running this code on old kernel, swapon() return EINVAL.
At that time, we should fall back swapon(0x10000).
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WARNING: multiple messages have this Message-ID (diff)
From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
To: Rafael Aquini <aquini@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, hughd@google.com, shli@kernel.org,
kzak@redhat.com, jmoyer@redhat.com, riel@redhat.com,
lwoodman@redhat.com, mgorman@suse.de, kosaki.motohiro@gmail.com
Subject: Re: [RFC PATCH 02/02] swapon: add "cluster-discard" support
Date: Mon, 20 May 2013 21:02:43 -0400 [thread overview]
Message-ID: <519AC7B3.5060902@gmail.com> (raw)
In-Reply-To: <398ace0dd3ca1283372b3aad3fceeee59f6897d7.1369084886.git.aquini@redhat.com>
> +.B "\-c, \-\-cluster\-discard"
> +Swapping will discard clusters of swap pages in between freeing them
> +and re-writing to them, if the swap device supports that. This option
> +also implies the
> +.I \-d, \-\-discard
> +swapon flag.
I'm not sure this is good idea. Why can't we make these flags orthogonal?
> /* If true, don't complain if the device/file doesn't exist */
> static int ifexists;
> @@ -570,8 +574,11 @@ static int do_swapon(const char *orig_special, int prio,
> << SWAP_FLAG_PRIO_SHIFT);
> }
> #endif
> - if (fl_discard)
> + if (fl_discard) {
> flags |= SWAP_FLAG_DISCARD;
> + if (fl_discard > 1)
> + flags |= SWAP_FLAG_DISCARD_CLUSTER;
This is not enough, IMHO. When running this code on old kernel, swapon() return EINVAL.
At that time, we should fall back swapon(0x10000).
next prev parent reply other threads:[~2013-05-21 1:02 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-21 0:04 [RFC PATCH 00/02] swap: allowing a more flexible DISCARD policy Rafael Aquini
2013-05-21 0:04 ` Rafael Aquini
2013-05-21 0:04 ` [RFC PATCH 01/02] swap: discard while swapping only if SWAP_FLAG_DISCARD_CLUSTER Rafael Aquini
2013-05-21 0:04 ` Rafael Aquini
2013-05-21 0:55 ` KOSAKI Motohiro
2013-05-21 0:55 ` KOSAKI Motohiro
2013-05-21 21:06 ` Rafael Aquini
2013-05-21 21:06 ` Rafael Aquini
2013-05-21 0:04 ` [RFC PATCH 02/02] swapon: add "cluster-discard" support Rafael Aquini
2013-05-21 0:04 ` Rafael Aquini
2013-05-21 1:02 ` KOSAKI Motohiro [this message]
2013-05-21 1:02 ` KOSAKI Motohiro
2013-05-21 10:26 ` Karel Zak
2013-05-21 10:26 ` Karel Zak
2013-05-21 20:17 ` KOSAKI Motohiro
2013-05-21 20:17 ` KOSAKI Motohiro
2013-05-21 21:13 ` Rafael Aquini
2013-05-21 21:13 ` Rafael Aquini
2013-05-21 22:01 ` KOSAKI Motohiro
2013-05-21 22:01 ` KOSAKI Motohiro
2013-05-22 13:52 ` Jeff Moyer
2013-05-22 13:52 ` Jeff Moyer
2013-05-21 10:13 ` Karel Zak
2013-05-21 10:13 ` Karel Zak
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