Comment 17 for bug 654764

I'm using eCryptfs on top of ext4 on a Crucial C300 256GB SDD. For the first couple of months, I had the ext4 filesystem mounted with option discard and I was very disappointed by the performance. Specifically, in KMail, jumping through unread messages, stored in my eCryptfs HOME, was accompanied by a very disruptive lag. Listing a directory on the command line (ls) the first time had a similar lag.

SSDs are supposed to be fast, aren't they? I was resigned to accept this as the price I had to pay for encryption. A few weeks ago, triggered by another discussion, I mounted the ext4 fs without discard. The effect is extremely noticeable: there are no lags anymore, everything happens instantly. I gladly exchange this newfound speed for running fstrim every now and then.

I haven't undertaken any measurements as I didn't need any more convincing. In particular, I can't say whether eCryptfs was at all implicated in the lags I observed. The bit of advice I have to offer is to try and mount the SSD without discard and see if the performance improves.