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Groups > linux.kernel > #1631084 > unrolled thread
| Started by | js1304@gmail.com |
|---|---|
| First post | 2017-04-26 03:00 +0200 |
| Last post | 2017-04-27 10:00 +0200 |
| Articles | 2 on this page of 22 — 4 participants |
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[PATCH v4 0/4] zram: implement deduplication in zram js1304@gmail.com - 2017-04-26 03:00 +0200
[PATCH v4 2/4] zram: implement deduplication in zram js1304@gmail.com - 2017-04-26 03:00 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-26 04:20 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Joonsoo Kim <js1304@gmail.com> - 2017-04-26 08:00 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Minchan Kim <minchan@kernel.org> - 2017-04-26 08:30 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Joonsoo Kim <js1304@gmail.com> - 2017-04-26 09:10 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-26 09:30 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Minchan Kim <minchan@kernel.org> - 2017-04-26 09:50 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-26 09:20 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-26 04:40 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-26 08:10 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Joonsoo Kim <js1304@gmail.com> - 2017-04-26 08:10 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-26 06:10 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Joonsoo Kim <js1304@gmail.com> - 2017-04-26 08:10 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-26 08:30 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Joonsoo Kim <js1304@gmail.com> - 2017-04-27 09:00 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-27 09:50 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Joonsoo Kim <js1304@gmail.com> - 2017-05-02 07:40 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-26 06:30 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Joonsoo Kim <js1304@gmail.com> - 2017-04-26 08:10 +0200
Re: [PATCH v4 2/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-26 08:20 +0200
Re: [PATCH v4 0/4] zram: implement deduplication in zram Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-27 10:00 +0200
Page 2 of 2 — ← Prev page 1 [2]
| From | Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> |
|---|---|
| Date | 2017-04-26 08:20 +0200 |
| Subject | Re: [PATCH v4 2/4] zram: implement deduplication in zram |
| Message-ID | <tAosV-6T6-3@gated-at.bofh.it> |
| In reply to | #1631170 |
On (04/26/17 15:08), Joonsoo Kim wrote:
> > > +struct zram_hash {
> > > + spinlock_t lock;
> > > + struct rb_root rb_root;
> > > };
> >
> > just a note.
> >
> > we can easily have N CPUs spinning on ->lock for __zram_dedup_get() lookup,
> > which can invole a potentially slow zcomp_decompress() [zlib, for example,
> > with 64k pages] and memcmp(). the larger PAGE_SHIFT is, the more serialized
> > IOs become. in theory, at least.
> >
> > CPU0 CPU1 ... CPUN
> >
> > __zram_bvec_write() __zram_bvec_write() __zram_bvec_write()
> > zram_dedup_find() zram_dedup_find() zram_dedup_find()
> > spin_lock(&hash->lock);
> > spin_lock(&hash->lock); spin_lock(&hash->lock);
> > __zram_dedup_get()
> > zcomp_decompress()
> > ...
> >
> >
> > so may be there is a way to use read-write lock instead on spinlock for hash
> > and reduce write/read IO serialization.
>
> In fact, dedup release hash->lock before doing zcomp_decompress(). So,
> above contention cannot happen.
oh, my bad. you are right. somehow I didn't spot the unlock.
-ss
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| From | Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> |
|---|---|
| Date | 2017-04-27 10:00 +0200 |
| Message-ID | <tAMvf-5Tv-9@gated-at.bofh.it> |
| In reply to | #1631084 |
On (04/26/17 09:52), js1304@gmail.com wrote: > From: Joonsoo Kim <iamjoonsoo.kim@lge.com> > > Changes from v3 > o fix module build problem > o make zram_dedup_enabled() statically return false if CONFIG_ZRAM_DEDUP=n the entire patch set Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> -ss
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