On Thu, May 8, 2014 at 2:24 PM, Minchan Kim <minchan@xxxxxxxxxx> wrote:
> On Wed, May 07, 2014 at 11:52:59PM +0900, Joonsoo Kim wrote:
>> >> Most popular use of zram is the in-memory swap for small embedded system
>> >> so I don't want to increase memory footprint without good reason although
>> >> it makes synthetic benchmark. Alhought it's 1M for 1G, it isn't small if we
>> >> consider compression ratio and real free memory after boot
>>
>> We can use bit spin lock and this would not increase memory footprint for 32 bit
>> platform.
>
> Sounds like a idea.
> Weijie, Do you mind testing with bit spin lock?
Yes, I re-test them.
This time, I test each case 10 times, and take the average(KS/s).
(the test machine and method are same like previous mail's)
Iozone test result:
Test BASE CAS spinlock rwlock bit_spinlock
--------------------------------------------------------------
Initial write 1381094 1425435 1422860 1423075 1421521
Rewrite 1529479 1641199 1668762 1672855 1654910
Read 8468009 11324979 11305569 11117273 10997202
Re-read 8467476 11260914 11248059 11145336 10906486
Reverse Read 6821393 8106334 8282174 8279195 8109186
Stride read 7191093 8994306 9153982 8961224 9004434
Random read 7156353 8957932 9167098 8980465 8940476
Mixed workload 4172747 5680814 5927825 5489578 5972253
Random write 1483044 1605588 1594329 1600453 1596010
Pwrite 1276644 1303108 1311612 1314228 1300960
Pread 4324337 4632869 4618386 4457870 4500166
Fio test result:
Test base CAS spinlock rwlock bit_spinlock
-------------------------------------------------------------
seq-write 933789 999357 1003298 995961 1001958
seq-read 5634130 6577930 6380861 6243912 6230006
seq-rw 1405687 1638117 1640256 1633903 1634459
rand-rw 1386119 1614664 1617211 1609267 1612471
The base is v3.15.0-rc3, the others are per-meta entry lock.
Every optimization method shows higher performance than the base, however,
it is hard to say which method is the most appropriate.
To bit_spinlock, the modified code is mainly like this:
+#define ZRAM_FLAG_SHIFT 16
+
enum zram_pageflags {
/* Page consists entirely of zeros */
- ZRAM_ZERO,
+ ZRAM_ZERO = ZRAM_FLAG_SHIFT + 1,
+ ZRAM_ACCESS,
__NR_ZRAM_PAGEFLAGS,
};
/* Allocated for each disk page */
struct table {
unsigned long handle;
- u16 size; /* object size (excluding header) */
- u8 flags;
+ unsigned long value;
} __aligned(4);
The lower ZRAM_FLAG_SHIFT bits of table.value is size, the higher bits
is for zram_pageflags. By this means, it doesn't increase any memory
overhead on both 32-bit and 64-bit system.
Any complaint or suggestions are welcomed.
>>
>> Thanks.
>>
>> --
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>
> --
> Kind regards,
> Minchan Kim
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