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Date: Wed, 16 Apr 2014 17:53:53 +0300 From: Sergey Senozhatsky <sergey.senozhatsky@...il.com> To: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com> Cc: Minchan Kim <minchan@...nel.org>, Sergey Senozhatsky <sergey.senozhatsky@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, Jerome Marchand <jmarchan@...hat.com>, Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org Subject: Re: [PATCHv9 0/7] add compressing abstraction and multi stream support On (04/16/14 15:53), Bartlomiej Zolnierkiewicz wrote: > Hi, > > I'm a bit late on this patch series (sorry for that) but why are we not > using Crypto API for compression algorithm selection and multi stream > support? Compared to the earlier patches for zram like the ones we did > in July 2013 [1] this patch series requires us to: > > - implement compression algorithm support for each algorithm separately > (when using Crypto API all compression algorithms supported by Crypto > API are supported automatically) > > - manually set the number of maximum active compression streams (earlier > patches using Crypto API needed a lot less code and automatically scaled > number of compression streams to number of online CPUs) Hello Bartlomiej, there was a short discussion of `custom solution' vs `crypto API'. personally, I was not impressed by Crypto API. basically it requires a) locking of transformation context (if we have only one tfm for everyone) or b) having some sort of a list of tfms or c) storing tfm in a per_cpu area. c) requires ZRAM block device to become CPU hotplug aware and to begin reacting on onlining/offlining of a CPU by allocating/deallocating of transformation context. allocating new tfm potentially could a problem if system is under memory pressure and ZRAM is used as a swap device. besides, c) also requires additional locking via get_cpu()/put_cpu() around every comp op. in overall, that was something that I wanted to avoid. current solution does not depend on CPU notifier (which is a good thing for a block device driver, imho) and, thus, looks simpler in some ways. yet we still have ability to scale. there was a patch that was letting ZRAM to automatically scale number of compression streams to number of online CPUs, but Minchan wanted explicit one-stream-only option for swap device use-case. the other thing to mention is that CPU offlining API was under rework at that time by Srivatsa S. Bhat (cpu_notifier_register_begin(), cpu_notifier_register_done()) due to discovered races, which resulted in a patchset of 50+ patches (every existing CPU notifier user, including zsmalloc) and that played as additional factor. -ss > From what I see the pros of the current patch series are: > > - dynamic selection of the compression algorithm > > - ability to limit number of active streams below tha number of online CPUs > > However I believe that both above features can be also implemented on top of > the code using Crypto API. What am I missing? > > [1] https://lkml.org/lkml/2013/7/30/365 > > Best regards, > -- > Bartlomiej Zolnierkiewicz > Samsung R&D Institute Poland > Samsung Electronics > > On Thursday, March 06, 2014 05:11:37 PM Minchan Kim wrote: > > Hello Sergey, > > > > Sorry for the late. > > > > Today, I tested this patch and confirm that it's really good. > > I send result for the record. > > > > In x86(4core and x2 hyper threading, i7, 2.8GHz), I did parallel 4 dd > > test with 200m file like below > > > > dd if=./test200m.file of=mnt/file1 bs=512k count=1024 oflag=direct & > > dd if=./test200m.file of=mnt/file2 bs=512k count=1024 oflag=direct & > > dd if=./test200m.file of=mnt/file3 bs=512k count=1024 oflag=direct & > > dd if=./test200m.file of=mnt/file4 bs=512k count=1024 oflag=direct & > > wait all backgroud job > > > > The result is > > > > When 1 max_comp_streams, elapsed time is 36.26s > > When 8 max_comp_streams, elapsed time is 4.09s > > > > In ARM(4core, ARMv7, 1.5GHz), I did iozone test. > > > > 1 max_comp_streams, 8 max_comp_streams > > ==Initial write ==Initial write > > records: 10 records: 10 > > avg: 141964.05 avg: 239632.54 > > std: 3532.11 (2.49%) std: 43863.53 (18.30%) > > max: 147900.45 max: 319046.62 > > min: 135363.73 min: 178929.40 > > ==Rewrite ==Rewrite > > records: 10 records: 10 > > avg: 144757.46 avg: 247410.80 > > std: 4019.19 (2.78%) std: 37378.42 (15.11%) > > max: 150757.72 max: 293284.84 > > min: 135127.55 min: 188984.27 > > ==Read ==Read > > records: 10 records: 10 > > avg: 208325.22 avg: 202894.24 > > std: 57072.62 (27.40%) std: 41099.56 (20.26%) > > max: 293428.96 max: 289581.12 > > min: 79445.37 min: 157478.27 > > ==Re-read ==Re-read > > records: 10 records: 10 > > avg: 204750.36 avg: 237406.96 > > std: 36959.99 (18.05%) std: 41518.36 (17.49%) > > max: 268399.89 max: 286898.13 > > min: 154831.28 min: 160326.88 > > ==Reverse Read ==Reverse Read > > records: 10 records: 10 > > avg: 215043.10 avg: 208946.35 > > std: 31239.60 (14.53%) std: 38859.74 (18.60%) > > max: 251564.57 max: 284481.31 > > min: 154719.20 min: 155024.33 > > ==Stride read ==Stride read > > records: 10 records: 10 > > avg: 227246.54 avg: 198925.10 > > std: 31105.89 (13.69%) std: 30721.86 (15.44%) > > max: 290020.34 max: 227178.70 > > min: 157399.46 min: 153592.91 > > ==Random read ==Random read > > records: 10 records: 10 > > avg: 238239.81 avg: 216298.41 > > std: 37276.91 (15.65%) std: 38194.73 (17.66%) > > max: 291416.20 max: 286345.37 > > min: 152734.23 min: 151871.52 > > ==Mixed workload ==Mixed workload > > records: 10 records: 10 > > avg: 208434.11 avg: 234355.66 > > std: 31385.40 (15.06%) std: 22064.02 (9.41%) > > max: 253990.11 max: 270412.58 > > min: 162041.47 min: 186052.12 > > ==Random write ==Random write > > records: 10 records: 10 > > avg: 142172.54 avg: 290231.28 > > std: 6233.67 (4.38%) std: 46462.35 (16.01%) > > max: 150652.40 max: 338096.54 > > min: 130584.14 min: 183253.25 > > ==Pwrite ==Pwrite > > records: 10 records: 10 > > avg: 141247.91 avg: 267085.70 > > std: 6756.08 (4.78%) std: 40019.39 (14.98%) > > max: 150239.13 max: 335512.33 > > min: 130456.98 min: 180832.45 > > ==Pread ==Pread > > records: 10 records: 10 > > avg: 214990.26 avg: 208730.94 > > std: 40701.79 (18.93%) std: 50797.78 (24.34%) > > max: 287060.54 max: 300675.25 > > min: 157642.17 min: 156763.98 > > > > So, all write test both x86 and ARM is really huge win > > and I couldn't find any regression! > > > > Thanks for nice work. > > > > For all patchset, > > > > Acked-by: Minchan Kim <minchan@...nel.org> > > > > On Fri, Feb 28, 2014 at 08:52:00PM +0300, Sergey Senozhatsky wrote: > > > This patchset introduces zcomp compression backend abstraction > > > adding ability to support compression algorithms other than LZO; > > > support for multi compression streams, making parallel compressions > > > possible; adds support for LZ4 compression algorithm. > > > > > > v8->v9 (reviewed by Andrew Morton): > > > -- add LZ4 backend (+iozone test vs LZO) > > > -- merge patches 'zram: document max_comp_streams' and 'zram: add multi > > > stream functionality' > > > -- do not extern backend struct from source file > > > -- use find()/release() naming instead of get()/put() > > > -- minor code, commit messages and code comments `nitpicks' > > > -- removed Acked-by Minchan Kim from first two patches, because I've > > > changed them a bit. > > > > > > v7->v8 (reviewed by Minchan Kim): > > > -- merge patches 'add multi stream functionality' and 'enable multi > > > stream compression support in zram' > > > -- return status code from set_max_streams knob and print message on > > > error > > > -- do not use atomic type for ->avail_strm > > > -- return back: allocate by default only one stream for multi stream backend > > > -- wake sleeping write in zcomp_strm_multi_put() only if we put stream > > > to idle list > > > -- minor code `nitpicks' > > > > > > v6->v7 (reviewed by Minchan Kim): > > > -- enable multi and single stream support out of the box (drop > > > ZRAM_MULTI_STREAM config option) > > > -- add set_max_stream knob, so we can adjust max number of compression > > > streams in runtime (for multi stream backend at the moment) > > > -- minor code `nitpicks' > > > > > > v5->v6 (reviewed by Minchan Kim): > > > -- handle single compression stream case separately, using mutex locking, > > > to address perfomance regression > > > -- handle multi compression stream using spin lock and wait_event()/wake_up() > > > -- make multi compression stream support configurable (ZRAM_MULTI_STREAM > > > config option) > > > > > > v4->v5 (reviewed by Minchan Kim): > > > -- renamed zcomp buffer_lock; removed src len and dst len from > > > compress() and decompress(); not using term `buffer' and > > > `workmem' in code and documentation; define compress() and > > > decompress() functions for LZO backend; not using goto's; > > > do not put idle zcomp_strm to idle list tail. > > > > > > v3->v4 (reviewed by Minchan Kim): > > > -- renamed compression backend and working memory structs as requested > > > by Minchan Kim; fixed several issues noted by Minchan Kim. > > > > > > Sergey Senozhatsky (7): > > > zram: introduce compressing backend abstraction > > > zram: use zcomp compressing backends > > > zram: factor out single stream compression > > > zram: add multi stream functionality > > > zram: add set_max_streams knob > > > zram: make compression algorithm selection possible > > > zram: add lz4 algorithm backend > > > > > > Documentation/ABI/testing/sysfs-block-zram | 17 +- > > > Documentation/blockdev/zram.txt | 45 +++- > > > drivers/block/zram/Kconfig | 10 + > > > drivers/block/zram/Makefile | 4 +- > > > drivers/block/zram/zcomp.c | 349 +++++++++++++++++++++++++++++ > > > drivers/block/zram/zcomp.h | 68 ++++++ > > > drivers/block/zram/zcomp_lz4.c | 47 ++++ > > > drivers/block/zram/zcomp_lz4.h | 17 ++ > > > drivers/block/zram/zcomp_lzo.c | 47 ++++ > > > drivers/block/zram/zcomp_lzo.h | 17 ++ > > > drivers/block/zram/zram_drv.c | 131 ++++++++--- > > > drivers/block/zram/zram_drv.h | 11 +- > > > 12 files changed, 715 insertions(+), 48 deletions(-) > > > create mode 100644 drivers/block/zram/zcomp.c > > > create mode 100644 drivers/block/zram/zcomp.h > > > create mode 100644 drivers/block/zram/zcomp_lz4.c > > > create mode 100644 drivers/block/zram/zcomp_lz4.h > > > create mode 100644 drivers/block/zram/zcomp_lzo.c > > > create mode 100644 drivers/block/zram/zcomp_lzo.h > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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