From: Tony Battersby <tonyb-vFAe+i1/wJI5UWNf+nJyDw@public.gmane.org>
To: Andy Shevchenko
<andy.shevchenko-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: "linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Chaitra P B
<chaitra.basappa-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>,
Suganath Prabu Subramani
<suganath-prabu.subramani-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>,
Sathya Prakash
<sathya.prakash-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>,
Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
"linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org"
<linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>,
"iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org"
<iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
"MPT-FusionLinux.pdl-dY08KVG/lbpWk0Htik3J/w@public.gmane.org"
<MPT-FusionLinux.pdl-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>,
Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Subject: Re: [PATCH v3 08/10] dmapool: improve accuracy of debug statistics
Date: Wed, 8 Aug 2018 09:18:48 -0400 [thread overview]
Message-ID: <99f91604-f7ea-aaaa-fc15-3c1264603d0b@cybernetics.com> (raw)
In-Reply-To: <CAHp75Vcnf8m0zW+8Y8=fTE+F_bDjmaQpR0s2qiTdkOzqe2+fBA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On 08/08/2018 05:54 AM, Andy Shevchenko wrote:
> On Tue, Aug 7, 2018 at 7:49 PM, Tony Battersby <tonyb@cybernetics.com> wrote:
>> The "total number of blocks in pool" debug statistic currently does not
>> take the boundary value into account, so it diverges from the "total
>> number of blocks in use" statistic when a boundary is in effect. Add a
>> calculation for the number of blocks per allocation that takes the
>> boundary into account, and use it to replace the inaccurate calculation.
>
>> + retval->blks_per_alloc =
>> + (allocation / boundary) * (boundary / size) +
>> + (allocation % boundary) / size;
> If boundary is guaranteed to be power of 2, this can avoid cost
> divisions (though it's a slow path anyway).
>
At this point in the function, boundary is guaranteed to be either a
power of 2 or equal to allocation, which might not be a power of 2. Not
worth special-casing a slow path.
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WARNING: multiple messages have this Message-ID (diff)
From: Tony Battersby <tonyb@cybernetics.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Sathya Prakash <sathya.prakash@broadcom.com>,
Chaitra P B <chaitra.basappa@broadcom.com>,
Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"MPT-FusionLinux.pdl@broadcom.com"
<MPT-FusionLinux.pdl@broadcom.com>
Subject: Re: [PATCH v3 08/10] dmapool: improve accuracy of debug statistics
Date: Wed, 8 Aug 2018 09:18:48 -0400 [thread overview]
Message-ID: <99f91604-f7ea-aaaa-fc15-3c1264603d0b@cybernetics.com> (raw)
In-Reply-To: <CAHp75Vcnf8m0zW+8Y8=fTE+F_bDjmaQpR0s2qiTdkOzqe2+fBA@mail.gmail.com>
On 08/08/2018 05:54 AM, Andy Shevchenko wrote:
> On Tue, Aug 7, 2018 at 7:49 PM, Tony Battersby <tonyb@cybernetics.com> wrote:
>> The "total number of blocks in pool" debug statistic currently does not
>> take the boundary value into account, so it diverges from the "total
>> number of blocks in use" statistic when a boundary is in effect. Add a
>> calculation for the number of blocks per allocation that takes the
>> boundary into account, and use it to replace the inaccurate calculation.
>
>> + retval->blks_per_alloc =
>> + (allocation / boundary) * (boundary / size) +
>> + (allocation % boundary) / size;
> If boundary is guaranteed to be power of 2, this can avoid cost
> divisions (though it's a slow path anyway).
>
At this point in the function, boundary is guaranteed to be either a
power of 2 or equal to allocation, which might not be a power of 2.A Not
worth special-casing a slow path.
next prev parent reply other threads:[~2018-08-08 13:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-07 16:49 [PATCH v3 08/10] dmapool: improve accuracy of debug statistics Tony Battersby
2018-08-07 16:49 ` Tony Battersby
[not found] ` <cbe2fb30-54b3-663e-4e30-448353723b8f-vFAe+i1/wJI5UWNf+nJyDw@public.gmane.org>
2018-08-08 9:54 ` Andy Shevchenko
2018-08-08 9:54 ` Andy Shevchenko
[not found] ` <CAHp75Vcnf8m0zW+8Y8=fTE+F_bDjmaQpR0s2qiTdkOzqe2+fBA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-08-08 13:18 ` Tony Battersby [this message]
2018-08-08 13:18 ` Tony Battersby
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