From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: pavel.tatashin@microsoft.com, linux-nvdimm@lists.01.org,
linux-kernel@vger.kernel.org, willy@infradead.org,
mingo@kernel.org, linux-mm@kvack.org, khalid.aziz@oracle.com,
rppt@linux.vnet.ibm.com, vbabka@suse.cz,
sparclinux@vger.kernel.org, akpm@linux-foundation.org,
ldufour@linux.vnet.ibm.com, mgorman@techsingularity.net,
davem@davemloft.net, kirill.shutemov@linux.intel.com
Subject: Re: [mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links
Date: Wed, 05 Dec 2018 09:55:17 -0800 [thread overview]
Message-ID: <19c9f0fe83a857d5858c386a08ca2ddeba7cf27b.camel@linux.intel.com> (raw)
In-Reply-To: <20181205172225.GT1286@dhcp22.suse.cz>
On Wed, 2018-12-05 at 18:22 +0100, Michal Hocko wrote:
> On Fri 30-11-18 13:53:18, Alexander Duyck wrote:
> > Modify the set_page_links function to include the setting of the reserved
> > flag via a simple AND and OR operation. The motivation for this is the fact
> > that the existing __set_bit call still seems to have effects on performance
> > as replacing the call with the AND and OR can reduce initialization time.
> >
> > Looking over the assembly code before and after the change the main
> > difference between the two is that the reserved bit is stored in a value
> > that is generated outside of the main initialization loop and is then
> > written with the other flags field values in one write to the page->flags
> > value. Previously the generated value was written and then then a btsq
> > instruction was issued.
> >
> > On my x86_64 test system with 3TB of persistent memory per node I saw the
> > persistent memory initialization time on average drop from 23.49s to
> > 19.12s per node.
>
> I have tried to explain why the whole reserved bit doesn't make much
> sense in this code several times already. You keep ignoring that and
> that is highly annoying. Especially when you add a tricky code to
> optimize something that is not really needed.
>
> Based on that I am not going to waste my time on other patches in this
> series to review and give feedback which might be ignored again.
I got your explanation. However Andrew had already applied the patches
and I had some outstanding issues in them that needed to be addressed.
So I thought it best to send out this set of patches with those fixes
before the code in mm became too stale. I am still working on what to
do about the Reserved bit, and plan to submit it as a follow-up set.
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm
next prev parent reply other threads:[~2018-12-05 17:55 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-30 21:52 [mm PATCH v6 0/7] Deferred page init improvements Alexander Duyck
2018-11-30 21:52 ` [mm PATCH v6 1/7] mm: Use mm_zero_struct_page from SPARC on all 64b architectures Alexander Duyck
2018-11-30 21:52 ` [mm PATCH v6 2/7] mm: Drop meminit_pfn_in_nid as it is redundant Alexander Duyck
2018-11-30 21:53 ` [mm PATCH v6 3/7] mm: Implement new zone specific memblock iterator Alexander Duyck
2018-11-30 21:53 ` [mm PATCH v6 4/7] mm: Initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections Alexander Duyck
2018-11-30 21:53 ` [mm PATCH v6 5/7] mm: Move hot-plug specific memory init into separate functions and optimize Alexander Duyck
2018-11-30 21:53 ` [mm PATCH v6 6/7] mm: Add reserved flag setting to set_page_links Alexander Duyck
2018-12-05 17:22 ` Michal Hocko
2018-12-05 17:55 ` Alexander Duyck [this message]
2018-12-05 20:42 ` Michal Hocko
2019-03-12 22:07 ` Andrew Morton
2019-03-12 22:50 ` Alexander Duyck
2019-03-13 16:33 ` Andrew Morton
2019-03-13 17:07 ` Alexander Duyck
2018-11-30 21:53 ` [mm PATCH v6 7/7] mm: Use common iterator for deferred_init_pages and deferred_free_pages Alexander Duyck
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=19c9f0fe83a857d5858c386a08ca2ddeba7cf27b.camel@linux.intel.com \
--to=alexander.h.duyck@linux.intel.com \
--cc=akpm@linux-foundation.org \
--cc=davem@davemloft.net \
--cc=khalid.aziz@oracle.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=ldufour@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-nvdimm@lists.01.org \
--cc=mgorman@techsingularity.net \
--cc=mhocko@kernel.org \
--cc=mingo@kernel.org \
--cc=pavel.tatashin@microsoft.com \
--cc=rppt@linux.vnet.ibm.com \
--cc=sparclinux@vger.kernel.org \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).