| Message ID | 20180417131246.434-2-nayna@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 2018-04-17 at 09:12 -0400, Nayna Jain wrote: > The TPM polling code in tpm_transmit sleeps in each loop iteration for > 5 msecs. However, the TPM might return earlier, and thus waiting for > 5 msecs adds an unnecessary delay. This patch reduces the polling sleep > time in tpm_transmit() from 5 msecs to 1 msecs. > > Additionally, this patch renames TPM_POLL_SLEEP and moves it to tpm.h as > an enum value. > > After this change, performance on a TPM 1.2 with an 8 byte burstcount > for 1000 extends improved from ~14 sec to ~10.7 sec. > > Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com> Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com> > --- > drivers/char/tpm/tpm-interface.c | 2 +- > drivers/char/tpm/tpm.h | 3 ++- > drivers/char/tpm/tpm_tis_core.c | 10 ++-------- > 3 files changed, 5 insertions(+), 10 deletions(-) > > diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c > index 9e80a953d693..a676d8ad5992 100644 > --- a/drivers/char/tpm/tpm-interface.c > +++ b/drivers/char/tpm/tpm-interface.c > @@ -470,7 +470,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space, > goto out; > } > > - tpm_msleep(TPM_TIMEOUT); > + tpm_msleep(TPM_TIMEOUT_POLL); > rmb(); > } while (time_before(jiffies, stop)); > > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h > index f895fba4e20d..7e797377e1eb 100644 > --- a/drivers/char/tpm/tpm.h > +++ b/drivers/char/tpm/tpm.h > @@ -53,7 +53,8 @@ enum tpm_const { > enum tpm_timeout { > TPM_TIMEOUT = 5, /* msecs */ > TPM_TIMEOUT_RETRY = 100, /* msecs */ > - TPM_TIMEOUT_RANGE_US = 300 /* usecs */ > + TPM_TIMEOUT_RANGE_US = 300, /* usecs */ > + TPM_TIMEOUT_POLL = 1 /* msecs */ > }; > > /* TPM addresses */ > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c > index da074e3db19b..021e6b68f2db 100644 > --- a/drivers/char/tpm/tpm_tis_core.c > +++ b/drivers/char/tpm/tpm_tis_core.c > @@ -31,12 +31,6 @@ > #include "tpm.h" > #include "tpm_tis_core.h" > > -/* This is a polling delay to check for status and burstcount. > - * As per ddwg input, expectation is that status check and burstcount > - * check should return within few usecs. > - */ > -#define TPM_POLL_SLEEP 1 /* msec */ > - > static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value); > > static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask, > @@ -90,7 +84,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, > } > } else { > do { > - tpm_msleep(TPM_POLL_SLEEP); > + tpm_msleep(TPM_TIMEOUT_POLL); > status = chip->ops->status(chip); > if ((status & mask) == mask) > return 0; > @@ -232,7 +226,7 @@ static int get_burstcount(struct tpm_chip *chip) > burstcnt = (value >> 8) & 0xFFFF; > if (burstcnt) > return burstcnt; > - tpm_msleep(TPM_POLL_SLEEP); > + tpm_msleep(TPM_TIMEOUT_POLL); > } while (time_before(jiffies, stop)); > return -EBUSY; > } -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Apr 17, 2018 at 09:12:45AM -0400, Nayna Jain wrote: > The TPM polling code in tpm_transmit sleeps in each loop iteration for > 5 msecs. However, the TPM might return earlier, and thus waiting for > 5 msecs adds an unnecessary delay. This patch reduces the polling sleep > time in tpm_transmit() from 5 msecs to 1 msecs. I'm not sure what TPM returning earlier has to do with this. TPM probably never returns exactly in the spec defined timeout/duration. I just don't understand reasoning in this paragraph. > Additionally, this patch renames TPM_POLL_SLEEP and moves it to tpm.h as > an enum value. > > After this change, performance on a TPM 1.2 with an 8 byte burstcount > for 1000 extends improved from ~14 sec to ~10.7 sec. You cannot give absolute numbers without a context (platform, software). > Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com> /Jarkko -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index 9e80a953d693..a676d8ad5992 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -470,7 +470,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space, goto out; } - tpm_msleep(TPM_TIMEOUT); + tpm_msleep(TPM_TIMEOUT_POLL); rmb(); } while (time_before(jiffies, stop)); diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index f895fba4e20d..7e797377e1eb 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -53,7 +53,8 @@ enum tpm_const { enum tpm_timeout { TPM_TIMEOUT = 5, /* msecs */ TPM_TIMEOUT_RETRY = 100, /* msecs */ - TPM_TIMEOUT_RANGE_US = 300 /* usecs */ + TPM_TIMEOUT_RANGE_US = 300, /* usecs */ + TPM_TIMEOUT_POLL = 1 /* msecs */ }; /* TPM addresses */ diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index da074e3db19b..021e6b68f2db 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -31,12 +31,6 @@ #include "tpm.h" #include "tpm_tis_core.h" -/* This is a polling delay to check for status and burstcount. - * As per ddwg input, expectation is that status check and burstcount - * check should return within few usecs. - */ -#define TPM_POLL_SLEEP 1 /* msec */ - static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value); static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask, @@ -90,7 +84,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, } } else { do { - tpm_msleep(TPM_POLL_SLEEP); + tpm_msleep(TPM_TIMEOUT_POLL); status = chip->ops->status(chip); if ((status & mask) == mask) return 0; @@ -232,7 +226,7 @@ static int get_burstcount(struct tpm_chip *chip) burstcnt = (value >> 8) & 0xFFFF; if (burstcnt) return burstcnt; - tpm_msleep(TPM_POLL_SLEEP); + tpm_msleep(TPM_TIMEOUT_POLL); } while (time_before(jiffies, stop)); return -EBUSY; }
The TPM polling code in tpm_transmit sleeps in each loop iteration for 5 msecs. However, the TPM might return earlier, and thus waiting for 5 msecs adds an unnecessary delay. This patch reduces the polling sleep time in tpm_transmit() from 5 msecs to 1 msecs. Additionally, this patch renames TPM_POLL_SLEEP and moves it to tpm.h as an enum value. After this change, performance on a TPM 1.2 with an 8 byte burstcount for 1000 extends improved from ~14 sec to ~10.7 sec. Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com> --- drivers/char/tpm/tpm-interface.c | 2 +- drivers/char/tpm/tpm.h | 3 ++- drivers/char/tpm/tpm_tis_core.c | 10 ++-------- 3 files changed, 5 insertions(+), 10 deletions(-)