From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>,
Minchan Kim <minchan@kernel.org>, Nitin Gupta <ngupta@vflare.org>,
RT <linux-rt-users@vger.kernel.org>
Subject: Re: [rfc patch] drivers/block/zram: Replace bit spinlocks with rtmutex for -rt
Date: Wed, 30 Mar 2016 11:19:39 +0200 [thread overview]
Message-ID: <56FB9A2B.3060903@linutronix.de> (raw)
In-Reply-To: <20160330091302.GB2769@swordfish>
On 03/30/2016 11:13 AM, Sergey Senozhatsky wrote:
> On (03/30/16 10:56), Sebastian Andrzej Siewior wrote:
> [..]
>>> +static inline void zram_unlock_table(struct zram_table_entry *table)
>>> +{
>>> + __clear_bit(ZRAM_ACCESS, &table->value);
>>> + spin_unlock(&table->lock);
>>> +}
>>
>> ZRAM_ACCESS is the only bit used for locking. ZRAM_ZERO is the only flag
>> set / tested.
>> Would it be possible to make value u32 and add a spinlock? value is has
>> not 64bit on 64bit systems and it uses only the first 23bits for the
>> size and bit 24+25 for the two flags we have now. So the size should not
>> change on 64bit systems only increase by four byte on 32bit systems.
>> That is without the lock debugging of course.
>>
>> Minchan, Nitin, Sergey do see any reason not to do so?
>
> that's increased size for every table entry + lock debugging bloat;
> not exactly what zram is trying to do. sounds bad enough.
That size is _only_ increased with lockdep enabled. So if you that much
concerned about size of this struct why not disable lockdep?
>
> -ss
>
Sebastian
next prev parent reply other threads:[~2016-03-30 9:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-22 10:19 [rfc patch] drivers/block/zram: Replace bit spinlocks with rtmutex for -rt Mike Galbraith
2016-03-22 10:34 ` Mike Galbraith
2016-03-30 8:56 ` Sebastian Andrzej Siewior
2016-03-30 9:13 ` Sergey Senozhatsky
2016-03-30 9:19 ` Sebastian Andrzej Siewior [this message]
2016-03-30 9:23 ` Mike Galbraith
2016-03-31 2:08 ` Mike Galbraith
2016-04-01 10:42 ` Sebastian Andrzej Siewior
2016-04-04 0:27 ` Sergey Senozhatsky
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