From: Jan Beulich <jbeulich@suse.com>
To: Juergen Gross <jgross@suse.com>
Cc: Dario Faggioli <dfaggioli@suse.com>,
George Dunlap <george.dunlap@citrix.com>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v2 05/17] xen/cpupool: switch cpupool list to normal list interface
Date: Tue, 1 Dec 2020 10:12:56 +0100 [thread overview]
Message-ID: <54301d8c-2d69-3206-6c42-d2638b7e7aa3@suse.com> (raw)
In-Reply-To: <20201201082128.15239-6-jgross@suse.com>
On 01.12.2020 09:21, Juergen Gross wrote:
> @@ -260,23 +257,42 @@ static struct cpupool *cpupool_create(
>
> spin_lock(&cpupool_lock);
>
> - for_each_cpupool(q)
> + if ( poolid != CPUPOOLID_NONE )
> {
> - last = (*q)->cpupool_id;
> - if ( (poolid != CPUPOOLID_NONE) && (last >= poolid) )
> - break;
> + q = __cpupool_find_by_id(poolid, false);
> + if ( !q )
> + list_add_tail(&c->list, &cpupool_list);
> + else
> + {
> + list_add_tail(&c->list, &q->list);
> + if ( q->cpupool_id == poolid )
> + {
> + *perr = -EEXIST;
> + goto err;
> + }
You bail _after_ having added the new entry to the list?
> + }
> +
> + c->cpupool_id = poolid;
> }
> - if ( *q != NULL )
> + else
> {
> - if ( (*q)->cpupool_id == poolid )
> + /* Cpupool 0 is created with specified id at boot and never removed. */
> + ASSERT(!list_empty(&cpupool_list));
> +
> + q = list_last_entry(&cpupool_list, struct cpupool, list);
> + /* In case of wrap search for first free id. */
> + if ( q->cpupool_id == CPUPOOLID_NONE - 1 )
> {
> - *perr = -EEXIST;
> - goto err;
> + list_for_each_entry(q, &cpupool_list, list)
> + if ( q->cpupool_id + 1 != list_next_entry(q, list)->cpupool_id )
> + break;
> }
> - c->next = *q;
> +
> + list_add(&c->list, &q->list);
> +
> + c->cpupool_id = q->cpupool_id + 1;
What guarantees that you managed to find an unused ID, other
than at current CPU speeds it taking too long to create 4
billion pools? Since you're doing this under lock, wouldn't
it help anyway to have a global helper variable pointing at
the lowest pool followed by an unused ID?
Jan
next prev parent reply other threads:[~2020-12-01 9:13 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 8:21 [PATCH v2 00/17] xen: support per-cpupool scheduling granularity Juergen Gross
2020-12-01 8:21 ` [PATCH v2 01/17] xen/cpupool: add cpu to sched_res_mask when removing it from cpupool Juergen Gross
2020-12-01 8:21 ` [PATCH v2 02/17] xen/cpupool: add missing bits for per-cpupool scheduling granularity Juergen Gross
2020-12-01 8:21 ` [PATCH v2 03/17] xen/cpupool: sort included headers in cpupool.c Juergen Gross
2020-12-01 8:21 ` [PATCH v2 04/17] xen/cpupool: switch cpupool id to unsigned Juergen Gross
2020-12-01 8:55 ` Jan Beulich
2020-12-01 9:01 ` Jürgen Groß
2020-12-01 9:07 ` Jan Beulich
2020-12-07 9:59 ` Jan Beulich
2020-12-07 14:48 ` Jürgen Groß
2020-12-07 15:00 ` Jan Beulich
2020-12-04 15:52 ` Dario Faggioli
2020-12-07 9:58 ` Jan Beulich
2020-12-07 15:21 ` Jan Beulich
2020-12-01 8:21 ` [PATCH v2 05/17] xen/cpupool: switch cpupool list to normal list interface Juergen Gross
2020-12-01 9:12 ` Jan Beulich [this message]
2020-12-01 9:18 ` Jürgen Groß
2020-12-04 16:13 ` Dario Faggioli
2020-12-04 16:16 ` Jürgen Groß
2020-12-04 16:25 ` Dario Faggioli
2020-12-04 16:56 ` Dario Faggioli
2020-12-01 8:21 ` [PATCH v2 06/17] xen/cpupool: use ERR_PTR() for returning error cause from cpupool_create() Juergen Gross
2020-12-02 8:58 ` Jan Beulich
2020-12-02 9:56 ` Jürgen Groß
2020-12-02 10:46 ` Jan Beulich
2020-12-02 10:58 ` Jürgen Groß
2020-12-04 16:29 ` Dario Faggioli
2020-12-01 8:21 ` [PATCH v2 07/17] xen/cpupool: support moving domain between cpupools with different granularity Juergen Gross
2020-12-01 8:21 ` [PATCH v2 08/17] docs: fix hypfs path documentation Juergen Gross
2020-12-01 8:21 ` [PATCH v2 09/17] xen/hypfs: move per-node function pointers into a dedicated struct Juergen Gross
2020-12-02 15:36 ` Jan Beulich
2020-12-02 15:41 ` Jürgen Groß
2020-12-03 8:47 ` Jürgen Groß
2020-12-03 9:12 ` Jan Beulich
2020-12-03 9:51 ` Jürgen Groß
2020-12-01 8:21 ` [PATCH v2 10/17] xen/hypfs: pass real failure reason up from hypfs_get_entry() Juergen Gross
2020-12-01 8:21 ` [PATCH v2 11/17] xen/hypfs: add getsize() and findentry() callbacks to hypfs_funcs Juergen Gross
2020-12-02 15:42 ` Jan Beulich
2020-12-02 15:51 ` Jürgen Groß
2020-12-03 8:12 ` Jan Beulich
2020-12-03 9:39 ` Jürgen Groß
2020-12-04 8:58 ` Jan Beulich
2020-12-04 11:14 ` Jürgen Groß
2020-12-01 8:21 ` [PATCH v2 12/17] xen/hypfs: add new enter() and exit() per node callbacks Juergen Gross
2020-12-03 14:59 ` Jan Beulich
2020-12-03 15:14 ` Jürgen Groß
2020-12-03 15:29 ` Jan Beulich
2020-12-04 8:33 ` Jürgen Groß
2020-12-04 8:30 ` Jan Beulich
2020-12-04 8:35 ` Jürgen Groß
2020-12-01 8:21 ` [PATCH v2 13/17] xen/hypfs: support dynamic hypfs nodes Juergen Gross
2020-12-03 15:08 ` Jan Beulich
2020-12-03 15:18 ` Jürgen Groß
2020-12-01 8:21 ` [PATCH v2 14/17] xen/hypfs: add support for id-based dynamic directories Juergen Gross
2020-12-03 15:44 ` Jan Beulich
2020-12-04 8:52 ` Jürgen Groß
2020-12-04 9:16 ` Jan Beulich
2020-12-04 13:08 ` Jürgen Groß
2020-12-07 7:54 ` Jan Beulich
2020-12-01 8:21 ` [PATCH v2 15/17] xen/cpupool: add cpupool directories Juergen Gross
2020-12-01 9:00 ` Jan Beulich
2020-12-01 9:03 ` Jürgen Groß
2020-12-02 15:46 ` Jürgen Groß
2020-12-03 14:46 ` Jan Beulich
2020-12-03 15:11 ` Jürgen Groß
2020-12-04 9:10 ` Jan Beulich
2020-12-04 11:08 ` Jürgen Groß
2020-12-04 11:54 ` Jan Beulich
2020-12-01 8:21 ` [PATCH v2 16/17] xen/cpupool: add scheduling granularity entry to cpupool entries Juergen Gross
2020-12-01 8:21 ` [PATCH v2 17/17] xen/cpupool: make per-cpupool sched-gran hypfs node writable Juergen Gross
2020-12-04 23:53 ` [PATCH v2 00/17] xen: support per-cpupool scheduling granularity Andrew Cooper
2020-12-05 7:41 ` Jürgen Groß
2020-12-07 9:00 ` Jan Beulich
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