Messages in this thread | | | Date | Mon, 17 Aug 2009 12:30:46 -0400 | From | Bill Davidsen <> | Subject | Re: Discard support (was Re: [PATCH] swap: send callback when swap slot is freed) |
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Mark Lord wrote: > Mark Lord wrote: > .. >> As you can see, we're now into the 100 millisecond range >> for successive TRIM-followed-by-TRIM commands. >> >> Those are all for single extents. I will follow-up with a small >> amount of similar data for TRIMs with multiple extents. > .. > > Here's the exact same TRIM ranges, but issued with *two* extents > per TRIM command, and again *without* the "sleep 1" between them: > > Beginning TRIM operations.. > Trimming 2 free extents encompassing 686 sectors (0 MB) > Trimming 2 free extents encompassing 236 sectors (0 MB) > Trimming 2 free extents encompassing 2186 sectors (1 MB) > Trimming 2 free extents encompassing 2206 sectors (1 MB) > Trimming 2 free extents encompassing 1494 sectors (1 MB) > Trimming 2 free extents encompassing 1086 sectors (1 MB) > Trimming 2 free extents encompassing 1658 sectors (1 MB) > Trimming 2 free extents encompassing 14250 sectors (7 MB) > Done. > [ 1528.761626] ata_qc_issue: ATA_CMD_DSM starting > [ 1528.761825] trim_completed: ATA_CMD_DSM took 419952 cycles > [ 1528.807158] ata_qc_issue: ATA_CMD_DSM starting > [ 1528.919035] trim_completed: ATA_CMD_DSM took 241772908 cycles > [ 1528.956048] ata_qc_issue: ATA_CMD_DSM starting > [ 1529.068536] trim_completed: ATA_CMD_DSM took 243085505 cycles > [ 1529.156661] ata_qc_issue: ATA_CMD_DSM starting > [ 1529.266377] trim_completed: ATA_CMD_DSM took 237098927 cycles > [ 1529.367212] ata_qc_issue: ATA_CMD_DSM starting > [ 1529.464676] trim_completed: ATA_CMD_DSM took 210619370 cycles > [ 1529.518619] ata_qc_issue: ATA_CMD_DSM starting > [ 1529.630444] trim_completed: ATA_CMD_DSM took 241654712 cycles > [ 1529.739335] ata_qc_issue: ATA_CMD_DSM starting > [ 1529.829826] trim_completed: ATA_CMD_DSM took 195545233 cycles > [ 1529.958442] ata_qc_issue: ATA_CMD_DSM starting > [ 1530.028356] trim_completed: ATA_CMD_DSM took 151077251 cycles > > Next, with *four* extents per TRIM: > > Beginning TRIM operations.. > Trimming 4 free extents encompassing 922 sectors (0 MB) > Trimming 4 free extents encompassing 4392 sectors (2 MB) > Trimming 4 free extents encompassing 2580 sectors (1 MB) > Trimming 4 free extents encompassing 15908 sectors (8 MB) > Done. > [ 1728.923119] ata_qc_issue: ATA_CMD_DSM starting > [ 1728.923343] trim_completed: ATA_CMD_DSM took 460590 cycles > [ 1728.975082] ata_qc_issue: ATA_CMD_DSM starting > [ 1729.087266] trim_completed: ATA_CMD_DSM took 242429200 cycles > [ 1729.170167] ata_qc_issue: ATA_CMD_DSM starting > [ 1729.282718] trim_completed: ATA_CMD_DSM took 243229428 cycles > [ 1729.382328] ata_qc_issue: ATA_CMD_DSM starting > [ 1729.481364] trim_completed: ATA_CMD_DSM took 214012942 cycles > > And with *eight* extents per TRIM: > Beginning TRIM operations.. > Trimming 8 free extents encompassing 5314 sectors (3 MB) > Trimming 8 free extents encompassing 18488 sectors (9 MB) > Done. > [ 1788.289669] ata_qc_issue: ATA_CMD_DSM starting > [ 1788.290247] trim_completed: ATA_CMD_DSM took 1228539 cycles > [ 1788.327223] ata_qc_issue: ATA_CMD_DSM starting > [ 1788.440490] trim_completed: ATA_CMD_DSM took 244773243 cycles > > And finally, with everything in a single TRIM: > > Beginning TRIM operations.. > Trimming 16 free extents encompassing 23802 sectors (12 MB) > Done. > [ 1841.561147] ata_qc_issue: ATA_CMD_DSM starting > [ 1841.563217] trim_completed: ATA_CMD_DSM took 4458480 cycles > > Notice how the first TRIM of each group above shows an artificially > short completion time, because the firmware seems to return "done" > before it's really done. Subsequent TRIMs seem to have to wait > for the previous one to really complete, and thus give more reliable > timing data for our purposes.
I assume that it really is artificial, rather than the device really being ready for another operation (other than another TRIM). I lack the hardware, but the test would be the time to complete a read, trim and read, and two trim and read operations. Just my thought that the TRIM in progress may only block the next TRIM, rather than other operations.
-- bill davidsen <davidsen@tmr.com> CTO TMR Associates, Inc
"You are disgraced professional losers. And by the way, give us our money back." - Representative Earl Pomeroy, Democrat of North Dakota on the A.I.G. executives who were paid bonuses after a federal bailout.
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