On Mon, Jul 6, 2020 at 3:28 PM Bob Liu <bob.liu@xxxxxxxxxx> wrote: > > Hi Ignat, > > On 6/27/20 5:03 AM, Ignat Korchagin wrote: > > This is a follow up from [1]. Consider the following script: > > > > sudo modprobe brd rd_nr=1 rd_size=4194304 > > > > Did you test null_blk device? I didn't get result as expected using null_blk. I've modified the script in the patch description to use a null_blk device instead of /dev/ram0, but I created the block device with queue_mode=0. My results are as follows: reading from /dev/nullb0 READ: bw=527MiB/s (552MB/s), 527MiB/s-527MiB/s (552MB/s-552MB/s), io=92.6GiB (99.4GB), run=180000-180000msec reading from /dev/mapper/eram0 READ: bw=112MiB/s (117MB/s), 112MiB/s-112MiB/s (117MB/s-117MB/s), io=19.7GiB (21.1GB), run=180001-180001msec reading from /dev/mapper/eram0-inline-read READ: bw=288MiB/s (302MB/s), 288MiB/s-288MiB/s (302MB/s-302MB/s), io=50.6GiB (54.3GB), run=180000-180000msec reading from /dev/mapper/eram0-inline-write READ: bw=123MiB/s (129MB/s), 123MiB/s-123MiB/s (129MB/s-129MB/s), io=21.6GiB (23.1GB), run=180000-180000msec writing to /dev/nullb0 WRITE: bw=510MiB/s (535MB/s), 510MiB/s-510MiB/s (535MB/s-535MB/s), io=89.7GiB (96.3GB), run=180001-180001msec writing to /dev/mapper/eram0 WRITE: bw=45.9MiB/s (48.1MB/s), 45.9MiB/s-45.9MiB/s (48.1MB/s-48.1MB/s), io=8264MiB (8666MB), run=180001-180001msec writing to /dev/mapper/eram0-inline-read WRITE: bw=42.5MiB/s (44.6MB/s), 42.5MiB/s-42.5MiB/s (44.6MB/s-44.6MB/s), io=7658MiB (8030MB), run=180001-180001msec writing to /dev/mapper/eram0-inline-write WRITE: bw=259MiB/s (272MB/s), 259MiB/s-259MiB/s (272MB/s-272MB/s), io=45.6GiB (48.0GB), run=180000-180000msec Still see the same improvement. Can you retry your test with a queue_mode=0 null_blk device? Thanks, Ignat > 1. > # fio --filename=/dev/nullb0 --readwrite=readwrite --bs=4k --direct=1 --loops =1000000 --name=plain > Run status group 0 (all jobs): > READ: bw=390MiB/s (409MB/s), 390MiB/s-390MiB/s (409MB/s-409MB/s), io=10.6GiB (11.3GB), run=27744-27744msec > WRITE: bw=390MiB/s (409MB/s), 390MiB/s-390MiB/s (409MB/s-409MB/s), io=10.6GiB (11.3GB), run=27744-27744msec > > 2. > Create enctrypted-ram0 based on null_blk(without this patch): > # cryptsetup open --header crypthdr.img /dev/nullb0 encrypted-ram0 > # fio --filename=/dev/mapper/encrypted-ram0 --readwrite=readwrite --bs=4k --direct=1 --loops=1000000 --name=crypt > Run status group 0 (all jobs): > READ: bw=180MiB/s (188MB/s), 180MiB/s-180MiB/s (188MB/s-188MB/s), io=4534MiB (4754MB), run=25246-25246msec > WRITE: bw=179MiB/s (188MB/s), 179MiB/s-179MiB/s (188MB/s-188MB/s), io=4528MiB (4748MB), run=25246-25246msec > > 3. > Create enctrypted-ram0 based on null_blk(with this patch): > # cryptsetup open --header crypthdr.img /dev/nullb0 encrypted-ram0 > # fio --filename=/dev/mapper/encrypted-ram0 --readwrite=readwrite --bs=4k --direct=1 --loops=1000000 --name=crypt.patched > Run status group 0 (all jobs): > READ: bw=149MiB/s (156MB/s), 149MiB/s-149MiB/s (156MB/s-156MB/s), io=4128MiB (4329MB), run=27753-27753msec > WRITE: bw=149MiB/s (156MB/s), 149MiB/s-149MiB/s (156MB/s-156MB/s), io=4124MiB (4324MB), run=27753-27753msec > > Looks like the result is worse after this patch, or I may miss something.. > > Regards, > Bob > > > > echo '0 8388608 crypt capi:ecb(cipher_null) - 0 /dev/ram0 0' | \ > > sudo dmsetup create eram0 > > > > echo '0 8388608 crypt capi:ecb(cipher_null) - 0 /dev/ram0 0 1 no_write_workqueue' | \ > > sudo dmsetup create eram0-inline-write > > > > echo '0 8388608 crypt capi:ecb(cipher_null) - 0 /dev/ram0 0 1 no_read_workqueue' | \ > > sudo dmsetup create eram0-inline-read > > > > devices="/dev/ram0 /dev/mapper/eram0 /dev/mapper/eram0-inline-read " > > devices+="/dev/mapper/eram0-inline-write" > > > > for dev in $devices; do > > echo "reading from $dev" > > sudo fio --filename=$dev --readwrite=read --bs=4k --direct=1 \ > > --loops=1000000 --runtime=3m --name=plain | grep READ > > done > > > > for dev in $devices; do > > echo "writing to $dev" > > sudo fio --filename=$dev --readwrite=write --bs=4k --direct=1 \ > > --loops=1000000 --runtime=3m --name=plain | grep WRITE > > done > > > > This script creates a ramdisk (to eliminate hardware bias in the benchmark) and > > three dm-crypt instances on top. All dm-crypt instances use the NULL cipher > > to eliminate potentially expensive crypto bias (the NULL cipher just uses memcpy > > for "encyption"). The first instance is the current dm-crypt implementation from > > 5.8-rc2, the two others have new optional flags enabled, which bypass kcryptd > > workqueues for reads and writes respectively and write sorting for writes. On > > my VM (Debian in VirtualBox with 4 cores on 2.8 GHz Quad-Core Intel Core i7) I > > get the following output (formatted for better readability): > > > > reading from /dev/ram0 > > READ: bw=508MiB/s (533MB/s), 508MiB/s-508MiB/s (533MB/s-533MB/s), io=89.3GiB (95.9GB), run=180000-180000msec > > > > reading from /dev/mapper/eram0 > > READ: bw=80.6MiB/s (84.5MB/s), 80.6MiB/s-80.6MiB/s (84.5MB/s-84.5MB/s), io=14.2GiB (15.2GB), run=180000-180000msec > > > > reading from /dev/mapper/eram0-inline-read > > READ: bw=295MiB/s (309MB/s), 295MiB/s-295MiB/s (309MB/s-309MB/s), io=51.8GiB (55.6GB), run=180000-180000msec > > > > reading from /dev/mapper/eram0-inline-write > > READ: bw=114MiB/s (120MB/s), 114MiB/s-114MiB/s (120MB/s-120MB/s), io=20.1GiB (21.5GB), run=180000-180000msec > > > > writing to /dev/ram0 > > WRITE: bw=516MiB/s (541MB/s), 516MiB/s-516MiB/s (541MB/s-541MB/s), io=90.7GiB (97.4GB), run=180001-180001msec > > > > writing to /dev/mapper/eram0 > > WRITE: bw=40.4MiB/s (42.4MB/s), 40.4MiB/s-40.4MiB/s (42.4MB/s-42.4MB/s), io=7271MiB (7624MB), run=180001-180001msec > > > > writing to /dev/mapper/eram0-inline-read > > WRITE: bw=38.9MiB/s (40.8MB/s), 38.9MiB/s-38.9MiB/s (40.8MB/s-40.8MB/s), io=7000MiB (7340MB), run=180001-180001msec > > > > writing to /dev/mapper/eram0-inline-write > > WRITE: bw=277MiB/s (290MB/s), 277MiB/s-277MiB/s (290MB/s-290MB/s), io=48.6GiB (52.2GB), run=180000-180000msec > > > > Current dm-crypt implementation creates a significant IO performance overhead > > (at least on small IO block sizes) for both latency and throughput. We suspect > > offloading IO request processing into workqueues and async threads is more > > harmful these days with the modern fast storage. I also did some digging into > > the dm-crypt git history and much of this async processing is not needed > > anymore, because the reasons it was added are mostly gone from the kernel. More > > details can be found in [2] (see "Git archeology" section). > > > > This change adds no_(read|write)_workqueue flags separately for read and write > > BIOs, which direct dm-crypt not to offload crypto operations into kcryptd > > workqueues and process everything inline. In addition, writes are not buffered > > to be sorted in the dm-crypt red-black tree, but dispatched immediately. For > > cases, where crypto operations cannot happen inline (hard interrupt context, > > for example the read path of some NVME drivers), we offload the work to a > > tasklet rather than a workqueue. > > > > These flags ensure inline BIO processing in the dm-crypt module only. It is > > worth noting that some Crypto API implementations may offload encryption into > > their own workqueues, which are independent of the dm-crypt and its > > configuration. However upon enabling no_(read|write)_workqueue flags dm-crypt > > will instruct Crypto API not to backlog crypto requests. > > > > [1]: https://www.spinics.net/lists/dm-crypt/msg07516.html > > [2]: https://blog.cloudflare.com/speeding-up-linux-disk-encryption/ > > > > Signed-off-by: Ignat Korchagin <ignat@xxxxxxxxxxxxxx> > > --- > > drivers/md/dm-crypt.c | 68 +++++++++++++++++++++++++++++++++---------- > > 1 file changed, 52 insertions(+), 16 deletions(-) > > > > diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c > > index 000ddfab5ba0..6924eb49b1df 100644 > > --- a/drivers/md/dm-crypt.c > > +++ b/drivers/md/dm-crypt.c > > @@ -69,6 +69,7 @@ struct dm_crypt_io { > > u8 *integrity_metadata; > > bool integrity_metadata_from_pool; > > struct work_struct work; > > + struct tasklet_struct tasklet; > > > > struct convert_context ctx; > > > > @@ -127,7 +128,8 @@ struct iv_elephant_private { > > * and encrypts / decrypts at the same time. > > */ > > enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID, > > - DM_CRYPT_SAME_CPU, DM_CRYPT_NO_OFFLOAD }; > > + DM_CRYPT_SAME_CPU, DM_CRYPT_NO_OFFLOAD, > > + DM_CRYPT_NO_READ_WORKQUEUE, DM_CRYPT_NO_WRITE_WORKQUEUE }; > > > > enum cipher_flags { > > CRYPT_MODE_INTEGRITY_AEAD, /* Use authenticated mode for cihper */ > > @@ -1449,7 +1451,7 @@ static void kcryptd_async_done(struct crypto_async_request *async_req, > > int error); > > > > static void crypt_alloc_req_skcipher(struct crypt_config *cc, > > - struct convert_context *ctx) > > + struct convert_context *ctx, bool nobacklog) > > { > > unsigned key_index = ctx->cc_sector & (cc->tfms_count - 1); > > > > @@ -1463,12 +1465,12 @@ static void crypt_alloc_req_skcipher(struct crypt_config *cc, > > * requests if driver request queue is full. > > */ > > skcipher_request_set_callback(ctx->r.req, > > - CRYPTO_TFM_REQ_MAY_BACKLOG, > > + nobacklog ? 0 : CRYPTO_TFM_REQ_MAY_BACKLOG, > > kcryptd_async_done, dmreq_of_req(cc, ctx->r.req)); > > } > > > > static void crypt_alloc_req_aead(struct crypt_config *cc, > > - struct convert_context *ctx) > > + struct convert_context *ctx, bool nobacklog) > > { > > if (!ctx->r.req_aead) > > ctx->r.req_aead = mempool_alloc(&cc->req_pool, GFP_NOIO); > > @@ -1480,17 +1482,17 @@ static void crypt_alloc_req_aead(struct crypt_config *cc, > > * requests if driver request queue is full. > > */ > > aead_request_set_callback(ctx->r.req_aead, > > - CRYPTO_TFM_REQ_MAY_BACKLOG, > > + nobacklog ? 0 : CRYPTO_TFM_REQ_MAY_BACKLOG, > > kcryptd_async_done, dmreq_of_req(cc, ctx->r.req_aead)); > > } > > > > static void crypt_alloc_req(struct crypt_config *cc, > > - struct convert_context *ctx) > > + struct convert_context *ctx, bool nobacklog) > > { > > if (crypt_integrity_aead(cc)) > > - crypt_alloc_req_aead(cc, ctx); > > + crypt_alloc_req_aead(cc, ctx, nobacklog); > > else > > - crypt_alloc_req_skcipher(cc, ctx); > > + crypt_alloc_req_skcipher(cc, ctx, nobacklog); > > } > > > > static void crypt_free_req_skcipher(struct crypt_config *cc, > > @@ -1523,7 +1525,7 @@ static void crypt_free_req(struct crypt_config *cc, void *req, struct bio *base_ > > * Encrypt / decrypt data from one bio to another one (can be the same one) > > */ > > static blk_status_t crypt_convert(struct crypt_config *cc, > > - struct convert_context *ctx) > > + struct convert_context *ctx, bool noresched) > > { > > unsigned int tag_offset = 0; > > unsigned int sector_step = cc->sector_size >> SECTOR_SHIFT; > > @@ -1533,7 +1535,7 @@ static blk_status_t crypt_convert(struct crypt_config *cc, > > > > while (ctx->iter_in.bi_size && ctx->iter_out.bi_size) { > > > > - crypt_alloc_req(cc, ctx); > > + crypt_alloc_req(cc, ctx, noresched); > > atomic_inc(&ctx->cc_pending); > > > > if (crypt_integrity_aead(cc)) > > @@ -1566,7 +1568,8 @@ static blk_status_t crypt_convert(struct crypt_config *cc, > > atomic_dec(&ctx->cc_pending); > > ctx->cc_sector += sector_step; > > tag_offset++; > > - cond_resched(); > > + if (!noresched) > > + cond_resched(); > > continue; > > /* > > * There was a data integrity error. > > @@ -1879,6 +1882,9 @@ static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int async) > > unsigned long flags; > > sector_t sector; > > struct rb_node **rbp, *parent; > > + bool nosort = > > + (likely(!async) && test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags)) || > > + test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags); > > > > if (unlikely(io->error)) { > > crypt_free_buffer_pages(cc, clone); > > @@ -1892,7 +1898,7 @@ static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int async) > > > > clone->bi_iter.bi_sector = cc->start + io->sector; > > > > - if (likely(!async) && test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags)) { > > + if (nosort) { > > generic_make_request(clone); > > return; > > } > > @@ -1941,7 +1947,7 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io) > > sector += bio_sectors(clone); > > > > crypt_inc_pending(io); > > - r = crypt_convert(cc, &io->ctx); > > + r = crypt_convert(cc, &io->ctx, test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags)); > > if (r) > > io->error = r; > > crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending); > > @@ -1971,7 +1977,7 @@ static void kcryptd_crypt_read_convert(struct dm_crypt_io *io) > > crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio, > > io->sector); > > > > - r = crypt_convert(cc, &io->ctx); > > + r = crypt_convert(cc, &io->ctx, test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags)); > > if (r) > > io->error = r; > > > > @@ -2031,9 +2037,29 @@ static void kcryptd_crypt(struct work_struct *work) > > kcryptd_crypt_write_convert(io); > > } > > > > +static void kcryptd_crypt_tasklet(unsigned long work) > > +{ > > + kcryptd_crypt((struct work_struct *)work); > > +} > > + > > static void kcryptd_queue_crypt(struct dm_crypt_io *io) > > { > > struct crypt_config *cc = io->cc; > > + bool noworkqueue = > > + (bio_data_dir(io->base_bio) == READ && test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags)) || > > + (bio_data_dir(io->base_bio) == WRITE && test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags)); > > + > > + if (noworkqueue) { > > + if (in_irq()) { > > + /* Crypto API's "skcipher_walk_first() refuses to work in hard IRQ context */ > > + tasklet_init(&io->tasklet, kcryptd_crypt_tasklet, (unsigned long)&io->work); > > + tasklet_schedule(&io->tasklet); > > + return; > > + } > > + > > + kcryptd_crypt(&io->work); > > + return; > > + } > > > > INIT_WORK(&io->work, kcryptd_crypt); > > queue_work(cc->crypt_queue, &io->work); > > @@ -2838,7 +2864,7 @@ static int crypt_ctr_optional(struct dm_target *ti, unsigned int argc, char **ar > > struct crypt_config *cc = ti->private; > > struct dm_arg_set as; > > static const struct dm_arg _args[] = { > > - {0, 6, "Invalid number of feature args"}, > > + {0, 8, "Invalid number of feature args"}, > > }; > > unsigned int opt_params, val; > > const char *opt_string, *sval; > > @@ -2868,6 +2894,10 @@ static int crypt_ctr_optional(struct dm_target *ti, unsigned int argc, char **ar > > > > else if (!strcasecmp(opt_string, "submit_from_crypt_cpus")) > > set_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags); > > + else if (!strcasecmp(opt_string, "no_read_workqueue")) > > + set_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags); > > + else if (!strcasecmp(opt_string, "no_write_workqueue")) > > + set_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags); > > else if (sscanf(opt_string, "integrity:%u:", &val) == 1) { > > if (val == 0 || val > MAX_TAG_SIZE) { > > ti->error = "Invalid integrity arguments"; > > @@ -3196,6 +3226,8 @@ static void crypt_status(struct dm_target *ti, status_type_t type, > > num_feature_args += !!ti->num_discard_bios; > > num_feature_args += test_bit(DM_CRYPT_SAME_CPU, &cc->flags); > > num_feature_args += test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags); > > + num_feature_args += test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags); > > + num_feature_args += test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags); > > num_feature_args += cc->sector_size != (1 << SECTOR_SHIFT); > > num_feature_args += test_bit(CRYPT_IV_LARGE_SECTORS, &cc->cipher_flags); > > if (cc->on_disk_tag_size) > > @@ -3208,6 +3240,10 @@ static void crypt_status(struct dm_target *ti, status_type_t type, > > DMEMIT(" same_cpu_crypt"); > > if (test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags)) > > DMEMIT(" submit_from_crypt_cpus"); > > + if (test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags)) > > + DMEMIT(" no_read_workqueue"); > > + if (test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags)) > > + DMEMIT(" no_write_workqueue"); > > if (cc->on_disk_tag_size) > > DMEMIT(" integrity:%u:%s", cc->on_disk_tag_size, cc->cipher_auth); > > if (cc->sector_size != (1 << SECTOR_SHIFT)) > > @@ -3320,7 +3356,7 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits) > > > > static struct target_type crypt_target = { > > .name = "crypt", > > - .version = {1, 21, 0}, > > + .version = {1, 22, 0}, > > .module = THIS_MODULE, > > .ctr = crypt_ctr, > > .dtr = crypt_dtr, > > > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
