From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCH 3/6] zram: introduce ZRAM_IDLE flag
Date: Tue, 20 Nov 2018 11:46:59 +0900 [thread overview]
Message-ID: <20181120024659.GC4231@jagdpanzerIV> (raw)
In-Reply-To: <20181116072035.155108-4-minchan@kernel.org>
Hello,
On (11/16/18 16:20), Minchan Kim wrote:
[..]
> +static ssize_t idle_store(struct device *dev,
> + struct device_attribute *attr, const char *buf, size_t len)
> +{
> + struct zram *zram = dev_to_zram(dev);
> + unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
> + int index;
> +
> + down_read(&zram->init_lock);
> + if (!init_done(zram)) {
> + up_read(&zram->init_lock);
> + return -EINVAL;
> + }
> +
> + for (index = 0; index < nr_pages; index++) {
> + zram_slot_lock(zram, index);
> + if (!zram_allocated(zram, index))
> + goto next;
> +
> + zram_set_flag(zram, index, ZRAM_IDLE);
> +next:
> + zram_slot_unlock(zram, index);
> + }
> +
> + up_read(&zram->init_lock);
> +
> + return len;
> +}
This is one way of doing it.
The other one could, probabaly, be a bit more friendly to the cache
lines and CPU cycles. Basically, have a static timestamp variable,
which would keep the timestamp of last idle_store().
static idle_snapshot_ts;
static ssize_t idle_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t len)
{
idle_snapshot_ts = ktime();
}
And then in read_block_state() compare handle access time and
idle_snapshot_ts (if it's not 0). If the page was not modified/access
since the last idle_snapshot_ts (handle access time <= idle_snapshot_ts),
then it's idle, otherwise (handle access time > idle_snapshot_ts) it's
not idle.
Would this do the trick?
-ss
next prev parent reply other threads:[~2018-11-20 2:47 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-16 7:20 [PATCH 0/6] zram idle page writeback Minchan Kim
2018-11-16 7:20 ` [PATCH 1/6] zram: fix lockdep warning of free block handling Minchan Kim
2018-11-16 7:20 ` [PATCH 2/6] zram: refactoring flags and writeback stuff Minchan Kim
2018-11-16 7:20 ` [PATCH 3/6] zram: introduce ZRAM_IDLE flag Minchan Kim
2018-11-20 2:46 ` Sergey Senozhatsky [this message]
2018-11-22 5:11 ` Minchan Kim
2018-11-22 5:45 ` Sergey Senozhatsky
2018-11-16 7:20 ` [PATCH 4/6] zram: support idle page writeback Minchan Kim
2018-11-21 4:55 ` Sergey Senozhatsky
2018-11-21 13:34 ` Minchan Kim
2018-11-22 2:14 ` Sergey Senozhatsky
2018-11-22 5:04 ` Minchan Kim
2018-11-22 5:40 ` Sergey Senozhatsky
2018-11-22 6:15 ` Minchan Kim
2018-11-22 6:31 ` Minchan Kim
2018-11-22 6:59 ` Sergey Senozhatsky
2018-11-23 6:23 ` Minchan Kim
2018-11-16 7:20 ` [PATCH 5/6] zram: add bd_stat statistics Minchan Kim
2018-11-16 7:20 ` [PATCH 6/6] zram: writeback throttle Minchan Kim
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