From: Linus Torvalds <torvalds@linux-foundation.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Mark Hemment <markhemm@googlemail.com>,
Andrew Morton <akpm@linux-foundation.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
patrice.chotard@foss.st.com,
Mikulas Patocka <mpatocka@redhat.com>,
Lukas Czerner <lczerner@redhat.com>,
Christoph Hellwig <hch@lst.de>,
"Darrick J. Wong" <djwong@kernel.org>,
Chuck Lever <chuck.lever@oracle.com>,
Hugh Dickins <hughd@google.com>,
patches@lists.linux.dev, Linux-MM <linux-mm@kvack.org>,
mm-commits@vger.kernel.org, Mel Gorman <mgorman@suse.de>
Subject: Re: [patch 02/14] tmpfs: fix regressions from wider use of ZERO_PAGE
Date: Wed, 4 May 2022 14:09:52 -0700 [thread overview]
Message-ID: <CAHk-=wjUX5DGNSiBYvPC8fQJGRe5_RWR8NW=gYF4=UpPiwCE8A@mail.gmail.com> (raw)
In-Reply-To: <YnLplKy0Y66SsvQw@zn.tnic>
On Wed, May 4, 2022 at 2:01 PM Borislav Petkov <bp@alien8.de> wrote:
>
> I could try to do a perf probe or whatever fancy new thing we do now on
> clear_user to get some numbers of how many times it gets called during
> the benchmark run. Or do you wanna know the callers too?
One of the non-performance reasons I like inlined memcpy is actually
that when you do a regular 'perf record' run, the cost of the memcpy
gets associated with the call-site.
Which is universally what I want for those things. I used to love our
inlined spinlocks for the same reason back when we did them.
Yeah, yeah, you can do it with callchain magic, but then you get it
all - and I really consider memcpy/memset to be a special case.
Normally I want the "oh, that leaf function is expensive", but not for
memcpy and memset (and not for spinlocks, but we'll never go back to
the old trivial spinlocks)
I don't tend to particularly care about "how many times has this been
called" kind of trace profiles. It's the actual expense in CPU cycles
I tend to care about.
That said, I cared deeply about those kinds of CPU profiles when I was
working with Al on the RCU path lookup code and looking for where the
problem spots were.
That was years ago.
I haven't really done serious profiling work for a while (which is
just as well, because it's one of the things that went backwards when
I switch to the Zen 2 threadripper for my main machine)
Linus
next prev parent reply other threads:[~2022-05-04 21:10 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-15 2:12 incoming Andrew Morton
2022-04-15 2:13 ` [patch 01/14] MAINTAINERS: Broadcom internal lists aren't maintainers Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 02/14] tmpfs: fix regressions from wider use of ZERO_PAGE Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 22:10 ` Linus Torvalds
2022-04-15 22:21 ` Matthew Wilcox
2022-04-15 22:41 ` Hugh Dickins
2022-04-16 6:36 ` Borislav Petkov
2022-04-16 14:07 ` Mark Hemment
2022-04-16 17:28 ` Borislav Petkov
2022-04-16 17:42 ` Linus Torvalds
2022-04-16 21:15 ` Borislav Petkov
2022-04-17 19:41 ` Borislav Petkov
2022-04-17 20:56 ` Linus Torvalds
2022-04-18 10:15 ` Borislav Petkov
2022-04-18 17:10 ` Linus Torvalds
2022-04-19 9:17 ` Borislav Petkov
2022-04-19 16:41 ` Linus Torvalds
2022-04-19 17:48 ` Borislav Petkov
2022-04-21 15:06 ` Borislav Petkov
2022-04-21 16:50 ` Linus Torvalds
2022-04-21 17:22 ` Linus Torvalds
2022-04-24 19:37 ` Borislav Petkov
2022-04-24 19:54 ` Linus Torvalds
2022-04-24 20:24 ` Linus Torvalds
2022-04-27 0:14 ` Borislav Petkov
2022-04-27 1:29 ` Linus Torvalds
2022-04-27 10:41 ` Borislav Petkov
2022-04-27 16:00 ` Linus Torvalds
2022-05-04 18:56 ` Borislav Petkov
2022-05-04 19:22 ` Linus Torvalds
2022-05-04 20:18 ` Borislav Petkov
2022-05-04 20:40 ` Linus Torvalds
2022-05-04 21:01 ` Borislav Petkov
2022-05-04 21:09 ` Linus Torvalds [this message]
2022-05-10 9:31 ` clear_user (was: [patch 02/14] tmpfs: fix regressions from wider use of ZERO_PAGE) Borislav Petkov
2022-05-10 17:17 ` Linus Torvalds
2022-05-10 17:28 ` Linus Torvalds
2022-05-10 18:10 ` Borislav Petkov
2022-05-10 18:57 ` Borislav Petkov
2022-05-24 12:32 ` [PATCH] x86/clear_user: Make it faster Borislav Petkov
2022-05-24 16:51 ` Linus Torvalds
2022-05-24 17:30 ` Borislav Petkov
2022-05-25 12:11 ` Mark Hemment
2022-05-27 11:28 ` Borislav Petkov
2022-05-27 11:10 ` Ingo Molnar
2022-06-22 14:21 ` Borislav Petkov
2022-06-22 15:06 ` Linus Torvalds
2022-06-22 20:14 ` Borislav Petkov
2022-06-22 21:07 ` Linus Torvalds
2022-06-23 9:41 ` Borislav Petkov
2022-07-05 17:01 ` [PATCH -final] " Borislav Petkov
2022-07-06 9:24 ` Alexey Dobriyan
2022-07-11 10:33 ` Borislav Petkov
2022-07-12 12:32 ` Alexey Dobriyan
2022-08-06 12:49 ` Borislav Petkov
2022-08-18 10:44 ` [tip: x86/cpu] " tip-bot2 for Borislav Petkov
2022-04-15 2:13 ` [patch 03/14] mm/secretmem: fix panic when growing a memfd_secret Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 04/14] irq_work: use kasan_record_aux_stack_noalloc() record callstack Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 05/14] kasan: fix hw tags enablement when KUNIT tests are disabled Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 06/14] mm, kfence: support kmem_dump_obj() for KFENCE objects Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 07/14] mm, page_alloc: fix build_zonerefs_node() Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 08/14] mm: fix unexpected zeroed page mapping with zram swap Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 09/14] mm: compaction: fix compiler warning when CONFIG_COMPACTION=n Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 10/14] hugetlb: do not demote poisoned hugetlb pages Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 11/14] revert "fs/binfmt_elf: fix PT_LOAD p_align values for loaders" Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:13 ` [patch 12/14] revert "fs/binfmt_elf: use PT_LOAD p_align values for static PIE" Andrew Morton
2022-04-15 2:13 ` Andrew Morton
2022-04-15 2:14 ` [patch 13/14] mm/vmalloc: fix spinning drain_vmap_work after reading from /proc/vmcore Andrew Morton
2022-04-15 2:14 ` Andrew Morton
2022-04-15 2:14 ` [patch 14/14] mm: kmemleak: take a full lowmem check in kmemleak_*_phys() Andrew Morton
2022-04-15 2:14 ` Andrew Morton
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='CAHk-=wjUX5DGNSiBYvPC8fQJGRe5_RWR8NW=gYF4=UpPiwCE8A@mail.gmail.com' \
--to=torvalds@linux-foundation.org \
--cc=akpm@linux-foundation.org \
--cc=bp@alien8.de \
--cc=chuck.lever@oracle.com \
--cc=djwong@kernel.org \
--cc=hch@lst.de \
--cc=hughd@google.com \
--cc=lczerner@redhat.com \
--cc=linux-mm@kvack.org \
--cc=markhemm@googlemail.com \
--cc=mgorman@suse.de \
--cc=mm-commits@vger.kernel.org \
--cc=mpatocka@redhat.com \
--cc=patches@lists.linux.dev \
--cc=patrice.chotard@foss.st.com \
--cc=peterz@infradead.org \
--cc=x86@kernel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.