From: Raghavendra K T <raghavendra.kt@amd.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Ingo Molnar <mingo@redhat.com>, Mel Gorman <mgorman@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@redhat.com>,
rppt@kernel.org, Bharata B Rao <bharata@amd.com>,
Disha Talreja <dishaa.talreja@amd.com>
Subject: Re: [PATCH V2 2/3] sched/numa: Enhance vma scanning logic
Date: Sat, 4 Feb 2023 23:48:30 +0530 [thread overview]
Message-ID: <8c8f82c3-1296-ca28-0a21-6c5467ac2e3e@amd.com> (raw)
In-Reply-To: <Y9zvm4aB2B412drn@hirez.programming.kicks-ass.net>
On 2/3/2023 4:57 PM, Peter Zijlstra wrote:
> On Fri, Feb 03, 2023 at 12:15:48PM +0100, Peter Zijlstra wrote:
>
>>> +static inline void vma_set_active_pid_bit(struct vm_area_struct *vma)
>>> +{
>>> + unsigned int active_pid_bit;
>>> +
>>> + if (vma->numab) {
>>> + active_pid_bit = current->pid % BITS_PER_LONG;
>>> + vma->numab->accessing_pids |= 1UL << active_pid_bit;
>>> + }
>>> +}
>>
>> Perhaps:
>>
>> if (vma->numab)
>> __set_bit(current->pid % BITS_PER_LONG, &vma->numab->pids);
>>
>> ?
>>
>> Or maybe even:
>>
>> bit = current->pid % BITS_PER_LONG;
>> if (vma->numab && !__test_bit(bit, &vma->numab->pids))
>> __set_bit(bit, &vma->numab->pids);
>>
>
> The alternative to just taking the low n bits is to use:
>
> hash_32(current->pid, BITS_PER_LONG)
>
> That mixes things up a bit.
Good idea, when we have workloads that creates lesser number of threads
faster, current solution might have been simpler, but with thread
creation that happens over period of time hash function mixes and avoids
collision. will experiment with this option.
next prev parent reply other threads:[~2023-02-04 18:18 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-01 8:02 [PATCH V2 0/3] sched/numa: Enhance vma scanning Raghavendra K T
2023-02-01 8:02 ` [PATCH V2 1/3] sched/numa: Apply the scan delay to every vma instead of tasks Raghavendra K T
2023-02-03 10:24 ` Peter Zijlstra
2023-02-04 17:19 ` Raghavendra K T
2023-02-01 8:02 ` [PATCH V2 2/3] sched/numa: Enhance vma scanning logic Raghavendra K T
2023-02-03 11:15 ` Peter Zijlstra
2023-02-03 11:27 ` Peter Zijlstra
2023-02-04 18:18 ` Raghavendra K T [this message]
2023-02-04 18:14 ` Raghavendra K T
2023-02-07 6:41 ` Raghavendra K T
2023-02-27 6:40 ` Raghavendra K T
2023-02-27 10:06 ` Peter Zijlstra
2023-02-27 10:12 ` Raghavendra K T
2023-02-28 4:59 ` Raghavendra K T
2023-02-01 8:02 ` [PATCH V2 3/3] sched/numa: Reset the accessing PID information periodically Raghavendra K T
2023-02-03 11:35 ` Peter Zijlstra
2023-02-04 18:32 ` Raghavendra K T
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