From: David Sterba <dsterba@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>,
Maninder Singh <maninder1.s@samsung.com>,
herbert@gondor.apana.org.au, davem@davemloft.net,
keescook@chromium.org, gustavo@embeddedor.com, joe@perches.com,
linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
a.sahrawat@samsung.com, pankaj.m@samsung.com,
v.narang@samsung.com, Chris Mason <clm@fb.com>,
Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>,
linux-btrfs@vger.kernel.org, terrelln@fb.com
Subject: Re: [PATCH 1/4] zstd: pass pointer rathen than structure to functions
Date: Wed, 5 Jun 2019 14:32:53 +0200 [thread overview]
Message-ID: <20190605123253.GZ15290@suse.cz> (raw)
In-Reply-To: <20190605115703.GY15290@twin.jikos.cz>
On Wed, Jun 05, 2019 at 01:57:03PM +0200, David Sterba wrote:
> On Tue, Jun 04, 2019 at 03:43:26PM -0700, Andrew Morton wrote:
> > On Mon, 3 Jun 2019 14:32:03 +0530 Maninder Singh <maninder1.s@samsung.com> wrote:
> >
> > > currently params structure is passed in all functions, which increases
> > > stack usage in all the function and lead to stack overflow on target like
> > > ARM with kernel stack size of 8 KB so better to pass pointer.
> > >
> > > Checked for ARM:
> > >
> > > Original Patched
> > > Call FLow Size: 1264 1040
> > > ....
> > > (HUF_sort) -> 296
> > > (HUF_buildCTable_wksp) -> 144
> > > (HUF_compress4X_repeat) -> 88
> > > (ZSTD_compressBlock_internal) -> 200
> > > (ZSTD_compressContinue_internal)-> 136 -> 88
> > > (ZSTD_compressCCtx) -> 192 -> 64
> > > (zstd_compress) -> 144 -> 96
> > > (crypto_compress) -> 32
> > > (zcomp_compress) -> 32
> > > ....
> > >
> > > Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
> > > Signed-off-by: Vaneet Narang <v.narang@samsung.com>
> > >
> >
> > You missed btrfs. This needs review, please - particularly the
> > kernel-wide static ZSTD_parameters in zstd_get_btrfs_parameters().
>
> >
> > The base patch is here:
> >
> > http://lkml.kernel.org/r/1559552526-4317-2-git-send-email-maninder1.s@samsung.com
> >
> > --- a/fs/btrfs/zstd.c~zstd-pass-pointer-rathen-than-structure-to-functions-fix
> > +++ a/fs/btrfs/zstd.c
> > @@ -27,15 +27,17 @@
> > /* 307s to avoid pathologically clashing with transaction commit */
> > #define ZSTD_BTRFS_RECLAIM_JIFFIES (307 * HZ)
> >
> > -static ZSTD_parameters zstd_get_btrfs_parameters(unsigned int level,
> > +static ZSTD_parameters *zstd_get_btrfs_parameters(unsigned int level,
> > size_t src_len)
> > {
> > - ZSTD_parameters params = ZSTD_getParams(level, src_len, 0);
> > + static ZSTD_parameters params;
>
> > +
> > + params = ZSTD_getParams(level, src_len, 0);
>
> No thats' broken, the params can't be static as it depends on level and
> src_len. What happens if there are several requests in parallel with
> eg. different levels?
>
> Would be really great if the mailinglist is CCed when the code is
> changed in a non-trivial way.
So this does not compile fs/btrfs/zstd.o which Andrew probably found
too, otherwise btrfs is the only in-tree user of the function outside of
lib/ and crypto/.
I think that Nick Terrell should have been CCed too, as he ported zstd
to linux.
next prev parent reply other threads:[~2019-06-05 12:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20190603090227epcas5p348327061a3facbb9dfcf662bf2bc196e@epcas5p3.samsung.com>
2019-06-03 9:02 ` [PATCH 0/4] zstd: reduce stack usage Maninder Singh
[not found] ` <CGME20190603090232epcas5p1630d0584e8a1aa9495edc819605664fc@epcas5p1.samsung.com>
2019-06-03 9:02 ` [PATCH 1/4] zstd: pass pointer rathen than structure to functions Maninder Singh
2019-06-03 21:41 ` Andrew Morton
2019-06-04 22:43 ` Andrew Morton
2019-06-05 11:57 ` David Sterba
2019-06-05 12:32 ` David Sterba [this message]
2019-06-05 21:32 ` Andrew Morton
[not found] ` <CGME20190603090232epcas5p1630d0584e8a1aa9495edc819605664fc@epcms5p1>
2019-06-04 13:19 ` Vaneet Narang
2019-06-06 14:10 ` Vaneet Narang
2019-06-06 20:14 ` (2) " Nick Terrell
[not found] ` <CGME20190603090236epcas5p1bf0733024f7fb52f8129157b11c8f882@epcas5p1.samsung.com>
2019-06-03 9:02 ` [PATCH 2/4] zstd: use U16 data type for rankPos Maninder Singh
[not found] ` <CGME20190603090240epcas5p17d0881686df3fa3042d0b2d659e925b3@epcas5p1.samsung.com>
2019-06-03 9:02 ` [PATCH 3/4] zstd: move params structure to global variable to reduce stack usage Maninder Singh
2019-06-03 21:47 ` Andrew Morton
[not found] ` <CGME20190603090245epcas5p4a6cdfdb7ef72bfd36472f43bb4e1e0f1@epcas5p4.samsung.com>
2019-06-03 9:02 ` [PATCH 4/4] zstd: change structure variable from int to char Maninder Singh
2019-06-03 21:49 ` [PATCH 0/4] zstd: reduce stack usage Andrew Morton
[not found] ` <CGME20190603090227epcas5p348327061a3facbb9dfcf662bf2bc196e@epcms5p3>
2019-06-04 12:06 ` Vaneet Narang
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