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dkim=pass header.d=suse.com header.s=susede1 header.b=O3T7queS DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1721650624; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vN1oYJgnKGXgHS+7WZJ4Q18USh1zc0tS4qvELPG//0g=; b=O3T7queSEzN2XVVxG1f++WZkkjdp+K9+jUCCfCabUE6kDkip/ZXjYjQh5jSWg1a/bKhNKh zqAvjlvq1Xv8SMmB50p1oYh/B9Wng2HGgaH9Q9rV7ICEaBCEyXi8JueZ/53kTXZ+1Vhbzg GtYNCJPoLBSYtEtQOv9i/UKLTmOQPRg= From: Juergen Gross To: minios-devel@lists.xenproject.org, xen-devel@lists.xenproject.org Cc: samuel.thibault@ens-lyon.org, wl@xen.org, Juergen Gross Subject: [PATCH 3/3] mini-os: simplify monotonic_clock() Date: Mon, 22 Jul 2024 14:16:43 +0200 Message-ID: <20240722121643.18116-4-jgross@suse.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240722121643.18116-1-jgross@suse.com> References: <20240722121643.18116-1-jgross@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Spam-Score: -3.81 X-Rspamd-Action: no action X-Spam-Level: X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Queue-Id: 0B7A921849 X-Spamd-Result: default: False [-3.81 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; DWL_DNSWL_LOW(-1.00)[suse.com:dkim]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.com:dkim,suse.com:email]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; DKIM_TRACE(0.00)[suse.com:+] X-Spam-Flag: NO X-ZohoMail-DKIM: pass (identity @suse.com) (identity @suse.com) X-ZM-MESSAGEID: 1721650643072116600 Content-Type: text/plain; charset="utf-8" monotonic_clock() in arch/x86/time.c is more complex than needed: it has basically two nested loops making sure the time data obtained from Xen are valid. Simplify that by merging some of the used sub-functions into the main function and using only a single loop. Further simplify the code by using struct vcpu_time_info for the local instance instead of defining a similar structure in the code. Signed-off-by: Juergen Gross Reviewed-by: Samuel Thibault --- arch/x86/time.c | 58 ++++++++++++++----------------------------------- 1 file changed, 16 insertions(+), 42 deletions(-) diff --git a/arch/x86/time.c b/arch/x86/time.c index 7fd7abef..52916e15 100644 --- a/arch/x86/time.c +++ b/arch/x86/time.c @@ -44,24 +44,10 @@ *************************************************************************/ =20 /* These are peridically updated in shared_info, and then copied here. */ -struct shadow_time_info { - uint64_t tsc_timestamp; /* TSC at last update of time vals. */ - uint64_t system_timestamp; /* Time, in nanosecs, since boot. */ - uint32_t tsc_to_nsec_mul; - int tsc_shift; - uint32_t version; -}; static struct timespec shadow_ts; static uint32_t shadow_ts_version; =20 -static struct shadow_time_info shadow; - -static inline int time_values_up_to_date(void) -{ - struct vcpu_time_info *src =3D &HYPERVISOR_shared_info->vcpu_info[0].t= ime; - - return shadow.version =3D=3D src->version; -} +static struct vcpu_time_info shadow; =20 static inline int wc_values_up_to_date(void) { @@ -113,22 +99,7 @@ static unsigned long get_nsec_offset(void) rdtscll(now); delta =3D now - shadow.tsc_timestamp; =20 - return scale_delta(delta, shadow.tsc_to_nsec_mul, shadow.tsc_shift); -} - -static void get_time_values_from_xen(void) -{ - struct vcpu_time_info *src =3D &HYPERVISOR_shared_info->vcpu_info[0].t= ime; - - do { - shadow.version =3D src->version; - rmb(); - shadow.tsc_timestamp =3D src->tsc_timestamp; - shadow.system_timestamp =3D src->system_time; - shadow.tsc_to_nsec_mul =3D src->tsc_to_system_mul; - shadow.tsc_shift =3D src->tsc_shift; - rmb(); - } while ( (src->version & 1) | (shadow.version ^ src->version) ); + return scale_delta(delta, shadow.tsc_to_system_mul, shadow.tsc_shift); } =20 /* @@ -138,19 +109,22 @@ static void get_time_values_from_xen(void) */ uint64_t monotonic_clock(void) { - uint64_t time; - uint32_t local_time_version; + struct vcpu_time_info *src =3D &HYPERVISOR_shared_info->vcpu_info[0].t= ime; =20 - do { - local_time_version =3D shadow.version; - rmb(); - time =3D shadow.system_timestamp + get_nsec_offset(); - if ( !time_values_up_to_date() ) - get_time_values_from_xen(); - rmb(); - } while ( local_time_version !=3D shadow.version ); + if ( shadow.version !=3D src->version ) + { + do { + shadow.version =3D src->version; + rmb(); + shadow.tsc_timestamp =3D src->tsc_timestamp; + shadow.system_time =3D src->system_time; + shadow.tsc_to_system_mul =3D src->tsc_to_system_mul; + shadow.tsc_shift =3D src->tsc_shift; + rmb(); + } while ( (src->version & 1) || (shadow.version !=3D src->version)= ); + } =20 - return time; + return shadow.system_time + get_nsec_offset(); } =20 static void update_wallclock(void) --=20 2.43.0