From: "Huang\, Ying" <ying.huang@intel.com>
To: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>, Michal Hocko <mhocko@suse.com>,
Minchan Kim <minchan@kernel.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH -V2] swap: Reduce lock contention on swap cache from swap slots allocation
Date: Fri, 22 May 2020 13:58:40 +0800 [thread overview]
Message-ID: <877dx4ik8f.fsf@yhuang-dev.intel.com> (raw)
In-Reply-To: <20200521133532.psckytr456eevs5j@ca-dmjordan1.us.oracle.com> (Daniel Jordan's message of "Thu, 21 May 2020 09:35:32 -0400")
Daniel Jordan <daniel.m.jordan@oracle.com> writes:
> On Wed, May 20, 2020 at 11:15:02AM +0800, Huang Ying wrote:
>> @@ -2827,6 +2865,11 @@ static struct swap_info_struct *alloc_swap_info(void)
>> p = kvzalloc(struct_size(p, avail_lists, nr_node_ids), GFP_KERNEL);
>> if (!p)
>> return ERR_PTR(-ENOMEM);
>> + p->cluster_next_cpu = alloc_percpu(unsigned int);
>> + if (!p->cluster_next_cpu) {
>> + kvfree(p);
>> + return ERR_PTR(-ENOMEM);
>> + }
>
> There should be free_percpu()s at two places after this, but I think the
> allocation really belongs right...
>
>> @@ -3202,7 +3245,10 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
>> * select a random position to start with to help wear leveling
>> * SSD
>> */
>> - p->cluster_next = 1 + prandom_u32_max(p->highest_bit);
>
> ...here because then it's only allocated when it's actually used.
Good catch! And yes, this is the better place to allocate memory. I
will fix this in the new version! Thanks a lot!
Best Regards,
Huang, Ying
>> + for_each_possible_cpu(cpu) {
>> + per_cpu(*p->cluster_next_cpu, cpu) =
>> + 1 + prandom_u32_max(p->highest_bit);
>> + }
>> nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
>>
>> cluster_info = kvcalloc(nr_cluster, sizeof(*cluster_info),
>> --
>> 2.26.2
>>
>>
prev parent reply other threads:[~2020-05-22 5:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-20 3:15 [PATCH -V2] swap: Reduce lock contention on swap cache from swap slots allocation Huang Ying
2020-05-21 2:51 ` Andrew Morton
2020-05-21 3:24 ` Huang, Ying
2020-06-24 3:31 ` Huang, Ying
2020-05-21 13:35 ` Daniel Jordan
2020-05-22 5:58 ` Huang, Ying [this message]
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