The 179148 failures on 'access' system call is due to access check of two
files - the journal file and the wal-file.
The journal mode was OFF as also WAL mode.
Why is sqlite checking access permissions for this file 179140 times?
Removing or optimising this will make it faster by 20% atleast!
access("/dev/shm/test.db-journal", F_OK) = -1 ENOENT (No such file or
directory)
access("/dev/shm/test.db-wal", F_OK) = -1 ENOENT (No such file or
directory)
-Sreekumar
On Wed, Aug 10, 2011 at 5:28 PM, Sreekumar TP <[email protected]>wrote:
> Hi,
>
> I have the results from the tests (below). Alot of the time is spent in
> checking file permissions and locking the file (40 %).
>
>
> Inmem
>
> % time seconds usecs/call calls errors syscall
>
> ------ ----------- ----------- --------- --------- ----------------
>
> 28.53 0.124727 1 118524 write
>
> 23.42 0.102382 0 414624 gettimeofday
>
> 20.78 0.090840 1 76513 read
>
> 13.72 0.059977 0 191255 _llseek
>
>
>
> Db in tmpfs
>
> % time seconds usecs/call calls errors syscall
>
> ------ ----------- ----------- --------- --------- ----------------
>
> 21.83 0.257073 1 263306 write
>
> 21.18 0.249488 1 179148 179148 access
>
> 20.61 0.242725 0 509292 fcntl64
>
> 13.04 0.153551 0 448720 _llseek
>
> 9.44 0.111194 1 189370 read
>
> 8.16 0.096124 0 414624 gettimeofday
> 2.55 0.030000 3750 8 fdatasync
>
> On Tue, Aug 9, 2011 at 7:34 PM, Pavel Ivanov <[email protected]> wrote:
>
>> > Journal mode is WAL
>>
>> I believe in-memory database can't have journal mode WAL. So you
>> compare completely different settings.
>>
>>
>> Pavel
>>
>>
>> On Tue, Aug 9, 2011 at 5:15 AM, <[email protected]> wrote:
>> >
>> > Journal mode is WAL
>> >
>> >
>> > ------Original Message------
>> > From: Roger Binns
>> > Sender: [email protected]
>> > To: General Discussion of SQLite Database
>> > ReplyTo: General Discussion of SQLite Database
>> > Subject: Re: [sqlite] In memory v/s tmpfs
>> > Sent: Aug 9, 2011 2:42 PM
>> >
>> > -----BEGIN PGP SIGNED MESSAGE-----
>> > Hash: SHA1
>> >
>> > On 08/08/2011 06:34 PM, [email protected] wrote:
>> >> From the point of view of performance, I expected similar performance ,
>> tmpfs being a little slower due to filesystem overhead. However, the
>> operations on tmpfs was much slower than expected.
>> >
>> > Using tmpfs requires many kernel calls which is considerably more effort
>> > than the occasional malloc call. Additionally files have to be locked,
>> > journals made etc (you didn't mention your journal setting).
>> >
>> > Roger
>> > -----BEGIN PGP SIGNATURE-----
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>> > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
>> >
>> > iEYEARECAAYFAk5A+g0ACgkQmOOfHg372QTR8ACgqNeeuOxHRy7+hMH5RY/OAyV2
>> > Wq0AoMaSRtoFN4obCgmgHlpHthd9z5Zp
>> > =pkJt
>> > -----END PGP SIGNATURE-----
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>
>
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