Matthew "willy" Wilcox of Intel discussed around optimizing Solid State Disk performance (SSD) behaviors and "modeling" that behavior are still of interest. File systems developers need to understand how the performance costs have shifted compared to regular disks. Willy noted the Intel SSDs are adaptive and determine the alignment of partitions (63 sectors/track) based on the first read requests. The "adapted" behavior can be "reset" by issuing SECURE_ERASE to the device. Ric Wheeler (RedHat) also raised concerns about current use of fallocate() and how adding use of "TRIM" to fallocate() would affect "Thin Client Provisioning." Consensus was any form of over subscription of HW would cause problems and TRIM command might exacerbate those issues. But TRIM would have measurable positive impact for most users (of SSDs). Ted Ts'o expected ext4 to already properly issue TRIM at the right times.
More info: Google OS Blog